Yeah, It is possible, but very rare. That's happen to me before. It is really hurt and uncomfortable. But the contact lenses not lost, they still in your eyes. So, try to find out in your eyes and get it rid of your eyes. Just keep blinking your eyes or use some eye drops, it will help you find out the contact lenses.
Actually, I had this situation before and I felt extremely uncomfortable with my eyes. At that time, I thought the contact lenses must go behind my eyes, but don't panic, actually, the lens cannot. My optical doctor told me that they may slide under our eyelids or even become displaced when it occurs, thus, what you need to do is trying to look in the direction of the lenses to let it move back to the correct position. From my own experience, just keep blinking so that it is easier to migrate back down eventually.