Here are some common question that are asked in these situations.
Have you reset Restarted both your computer and the access point?
Were you able to connect before this problem? Then has anything changed? Your computer or the WiFi Access Point? If you were able to connect once before clear the saved connection settings in windows.
(Control Panel then the Network and Sharing center, look left and choose "manage network connections" at the connections window just right click on one of the connections and delete the connection in question)
These steps should work but if not can you give us more information on your problem? Like are other devices able to connect to the wireless access point?
