Check out this Mythbusters episode where they test out various hypnosis myths. If you don't want to watch the full episode, then forward to 5 minutes 25 seconds. Forward again to 14 minutes 40 - then 21 minutes 50
It shows that hypnosis cannot make a person do something against their will.
Forward again to 26 minutes 50 seconds for a hypnosis memory experiment - then 36 minutes 12 seconds. This shows that hypnosis can help with memory recall.
Enjoy!