If you can't connect to a wireless network, there may be an issue with your wireless adapter. Microsoft Support recommends resetting your wireless adapter to resolve issues like limited and slow connectivity or complete connection failure. The wireless adapter reset procedure for computers running Windows 7 is quick and straightforward, so you can get back to browsing the Internet in no time.
Open the "Control Panel" from the "Start" menu.
Type "adapter" into the Control Panel search box. From the search results listed, select the "View Network Connections" option from the "Network and Sharing Center" section.
Locate the icon of your wireless adapter in the window that opens.
Right-click the icon, and select "Disable" from the drop-down options. If a prompt appears, enter you administrator password to provide confirmation.
Right-click the icon again. Choose "Enable" from the drop-down menu. Enter your admin information again if the confirmation prompt appears.
Open a webpage to verify the reset and to test the connection.