hex editing help!

[CHEPE]

i tried to change my car using hexing, and now when ever i play (need for speed: most wanted) my car apears invisible does anyone know how i can fix it? i would really apreciate it!

[Kelmas]

Always make a backup before editing game files! This will save your time.

Try to remember which areas you have modified and edit HEX file again. I don't think there is any other way :|