If deleting is not long ago (less than a day), reboot your iPad, and wait for a few more hours. Your device needs some time to readjust.
If it's more than a day ago, connect your device to iTunes on a computer. Take a look at it's storage there. If there's some storage called "Other" (orange colour) with more than 2 GB, make sure there's a most recent backup, and restore it using iTunes.