Do something to help you come to terms and deal with your feelings. Maybe talk to someone about them, or write them down. You need to find closure, and to do that you need to deal with them instead of just thinking about them over and over again.
Time cures all I guess, but some stuff must be worked out within.... Maybe theres is something that you have guilt over or something like that try to find out why these things won't leave your mind. Some stuff can't be worked out immediately it is just healed through time... Good luck