I have suddenly lost the Wi-Fi on my iPad. Me and my friend have a Wi-Fi account with AT&T and his iPad Wi-Fi is working just fine. Why not mine?
You will need to restore your iPad. Hold down the top and bottom buttons till the screen goes black and you see the Apple symbol. Then follow the instructions on this page http://support.apple.com/kb/ht1808 to restore your iOS. I think once you do this and re-sync your ipad a lot of your problems (that you have posted about on here today) will be resolved.