If you can post a pic, it would help a lot of the affected area. Just goign by what you had said, and searching on google, I found out it's a 3ch coax, and the only thing I can see that would cause the head to come off like that would be either a missing bolt, or you have a busted head. And at $30, it's almost cheaper to buy another heli lol. My suggestion if you have to do this, is buy an mSR by Blade. It's the perfect beginner heli, and it's 4ch so it will help you move up in flying.
If I missed the pitch on teh head issue, post up a pic and I will see what I can find. Make sure it's good size.