It either fell out or unfortunately, got lodged behind your eye. You'd notice something if the lense got stuck behind your eye - it wouldn't feel right. Question: Were your eyes dry - meaning, is your other eye dry with the contract in. If it is, the other one could have easily fallen out or got stuck. I've been wearing contacts for over 20 years and have had my share of mishaps including the "behind the eye" problem. No, as far as I know, it won't cause any damage if it's stuck. It should work it's way out, but you may want to gently rub your eye and put solution in it too - it may help.