Thanks for the question. I understand that the Wi-Fi icon is no longer shown in your menubar. The following article outlines how to resolve this:
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.