cant connect to wifi after hard drive upgrade.

Hello there, Ohitsham.

It sounds like you are having issues with wi-fi connectivity on your MacBook Pro. The following Knowledge Base article offers up some great steps for troubleshooting:

How to troubleshoot Wi-Fi connectivity in OS X Lion or earlier

Preparation

First, determine what the issue is. Knowing what's wrong will help you identify appropriate troubleshooting steps.

1. Does the symptom occur with more than one Wi-Fi device?
   • Wi-Fi issues may be related to the network in question or they may be related to the Wi-Fi computer joining that network. Usually, if other computers or devices (such as the Apple TV or iPhone) are able to get on the Internet without issues, then your Wi-Fi router is probably fine.
   • If you only have one Wi-Fi device, proceed with this article.
2. Make sure your software is up-to-date.
   • Install all software updates available for your Mac.
   • If you use a third-party Wi-Fi router, check with the manufacturer to confirm that it has the latest firmware installed. If an update is available, follow the manufacturer's instructions for updating the firmware.
   • To determine if your Apple Wi-Fi base station firmware is up-to-date, see Updating your software.
3. Check your connections.

   Some networking issues may be caused by loose or disconnected cables. Verify that all Ethernet and power cables connected between your modem and your Wi-Fi router are correct. Checking that devices such as your router and modem are on, disconnecting and carefully reconnecting Ethernet cables, and/or replacing damaged Ethernet cables may resolve the issue without any further troubleshooting.

4. Verify that you are using the recommended settings for your device.

   See Recommended settings for Wi-Fi routers and access points.

5. Restart your network devices.

   Powering your modem or router off for a few seconds and then on again may resolve network issues without any additional troubleshooting. If you have phone service through your ISP, power cycling your modem may interrupt that service. You may need to contact your ISP in order to restore your phone service if your modem is reset or powered off. Ensure that you have alternative means to contact your ISP (such as a cell phone) to avoid unnecessary delays in restoring your Internet or phone service.

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Symptom: My Mac does not connect to the Internet

• Webpages do not open in Safari or other web browsers. These pages may be blank or you may receive an alert that "You are not connected to the Internet".
• Internet applications such as Mail, iChat, or the App Store cannot connect to their servers.

Note: Routers can be configured to allow some services to use the Internet (such as Mail) while preventing other services from using the Internet (such as web browsers). If you are not sure how your network is configured, contact your network administrator. If your network is not configured to block services, but some Internet applications work and others do not, then the issue is probably not related to your Wi-Fi network.

Solution

Use these steps if your computer cannot get online.

1. Make sure that Wi-Fi is on.Mac OS X allows you to turn your Wi-Fi (AirPort) card off entirely in case you do not wish to use it. Sometimes, the Wi-Fi card may be turned off accidentally. If your Wi-Fi interface is on and connected to a Wi-Fi network, the Wi-Fi menu will be bold. The Wi-Fi menu is in the top right corner of the screen.If your menu looks like the one above, then your computer is connected to a Wi-Fi network. Move to step 2 below.If Wi-Fi is off, choose Turn Wi-Fi On from the menu.Note: If the Wi-Fi menu icon includes an exclamation point, see this article.If the icon does not appear in the menu bar at all, then choose System Preferences from the Apple menu. Click the Network icon, then select Wi-Fi. Check the box next to "Show Wi-Fi status in menu bar."If your Wi-Fi interface does not appear in System Preferences, then you'll need to make sure that your Wi-Fi card is recognized by your Mac. Start from the installation media that came with your computer, or from the Recovery HD if OS X Lion is installed. Your computer should be able to access available networks.
2. If you are still not able to get online, make sure that your computer has joined the correct Wi-Fi network.Your Wi-Fi network should be listed in the Wi-Fi menu. The Wi-Fi network with which your Mac is associated will be checked, as shown below:Select your network if it is not chosen. If your Wi-Fi network is secured using a password, you will be prompted to enter a password as shown below.Note: If you do not know your network password, you will need to contact the administrator of your Wi-Fi network. If you are the administrator/owner of the network, you may need to configure your router in order to define the password for the network.Your Wi-Fi network may not be visible in the list. If the network is closed, it will not broadcast its network name. In order to join the Wi-Fi network, choose Join Other Network from the Wi-Fi menu. You will be prompted for the network name and security setting.Enter the name of your network and choose the Security your network uses.If your network is still not visible in your Wi-Fi network list, then it may be using an incompatible Wi-Fi standard. Most Macs support all common Wi-Fi standards. To check which standards your Mac supports, use Network Utility. Set the network interface to Wi-Fi and examine the information listed after "Model:"
3. If your computer has joined the correct Wi-Fi network but you are still unable to get online, you should check your TCP/IP settings in the Network pane of the System Preferences.
   1. Choose System Preferences from the Apple menu.
   2. Choose Network from the View menu.
   3. Select Wi-Fi, then click the Advanced button in the lower-left hand corner of the screen.
   4. Select the TCP/IP tab from the top of the screen.
   5. Your window should look like this (your IPv4 configuration may be different and your IPv4 address will definitely be different):
   6. If no IPv4 address appears, or if the IP address starts with "169.254.xxx.xxx", click "Renew DHCP Lease".
   7. Consult with your network administrator to determine the correct TCP/IP settings for your Wi-Fi network. Without the correct TCP/IP settings, your computer will not be able to get online.
   8. If your TCP/IP settings appear to be correct, and your computer still cannot access the Internet, check the DNS tab. See below for this tab. DNS is an Internet service that translates IP addresses into URLs and vice-versa. A correct DNS configuration allows your computer to connect to www.apple.com without having to enter the specific IP address of the Apple servers.
   9. You may want to contact your ISP for DNS addresses or use the DNS provided by a public service. To add a new DNS address, simply click the + button and enter the IP address for that DNS.
4. Try connecting to your router through Ethernet, if your Mac has Ethernet. Connect an Ethernet cable directly to your Wi-Fi router from your computer.
5. Check your range to the Wi-Fi router and reduce the effect of interference. If your computer is too far from your Wi-Fi router or your environment has too much Wi-Fi interference, then your computer may not detect the Wi-Fi network properly. The easiest way to check for range limits with your Wi-Fi network is to move your computer or your Wi-Fi router closer together and make sure that there are no obstructions (such as walls, cabinets, and so forth) between the router and your computer.See Potential sources of wireless interference for more information about interference, its causes and solutions.
6. Try connecting to a different Wi-Fi network.If your computer does not exhibit any symptoms when connected to a different Wi-Fi network, then the issue may be related to your network router or ISP. In that case, you should contact the manufacturer of your router or your ISP.

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If your symptom is not listed, or the above steps do not resolve the issue, search the Apple Support website for the symptom you are seeing or contact AppleCare for more help.

Thanks for being a part of Apple Support Communities.

Cheers.