My Gilera stalker cut out on me and wont start up again?

I was riding my moped(50cc Gilera Stalker) home one night when next thing i know it just completely cuts out on me. i tryed starting it up again at the time but it wasn't showing any signs of starting so i had to push it home. The next day it still wouldnt start and there was alot less compression in the kick than before the incident. The electric start still trys to start the bike so i dont hink it is a problem with the electrics. also i have changed the spark plug and it still wont start. Does anyone have any ideas as to how i can get it running again? Thank you