iPhone 4s will not notice wifi.

Hello Mike,

It sounds like your phone is not seeing your home network and cannot join it. I would use these troubleshooting steps from the following article named:

iOS: Troubleshooting Wi-Fi networks and connections

http://support.apple.com/kb/TS1398

1. Tap Settings > Wi-Fi and turn Wi-Fi off and on. If your Wi-Fi setting is dimmed, follow these steps.
2. Confirm that your Wi-Fi router and cable or DSL modem are connected to power, turned on, and connected to the Internet. If not, refer to your network administrator or Internet service provider (ISP) for assistance.
3. Restart your iOS device.
4. Turn your Wi-Fi router off and on2. If your ISP also provides cable or phone service, check with them before attempting this step to avoid interruption of service.
5. Update your device to the latest version of software.
6. Update your Wi-Fi router to the latest firmware2. For AirPort Base Stations, install updates using the AirPort Utility.

And

Unable to locate a Wi-Fi network

1. Verify that the network is available by tapping Settings > Wi-Fi and choosing from the available networks.Note: It may take a few seconds for the Wi-Fi network name to appear.
2. Move closer to your wireless router (access point) and attempt to locate the Wi-Fi network.
3. If you do not see the network you would like to join, you may be attempting to connect to a hidden network. Learn how to join a hidden network.
4. Supported Wi-Fi configurations vary by iOS device model. Find out which standards your device supports3.
5. Reset network settings by tapping Settings > General > Reset > Reset Network Settings. Note: This will reset all network settings including:
   • previously connected Wi-Fi networks and passwords
   • recently used Bluetooth accessories
   • VPN and APN settings

Thank you for using Apple Support Communities.

All the very best,

Sterling

Thank you for using the Apple Support Community. Due to the nature of your issue or question you may find more information by using another one of Apple's support resources - https://getsupport.apple.com/GetproductgroupList.action.