Did it ever connect? How about to other networks?
Try this:
Reboot ipad by pressing and holding both the home and sleep/wake buttons at the same time until the apple logo appears on the screen, then let go. Then try to connect to network.
Go to settings, Toggle airplane mode on/off. Make sure bluetooth is off. Turn on wif (airplane mode off). Try to connect.
Reset Network Settings
Go to settings/general/reset/reset network settings. Then try to connect to network.
If its your home router, then reboot router by unplugging for 5-10min. (do this while you're resetting network settings).
If problem persists, then check for firmware updates on your router.(you check router manufacturer support website for downloads and instructions).
When unable to connect to 802.11n WiFi Networks
http://support.apple.com/kb/TS3727?viewlocale=en_US&locale=en_US
Wifi Settings greyed out or dim
http://support.apple.com/kb/TS1559
Recommended wifi settings
http://support.apple.com/kb/HT4199