tao tao 125 won't go
 

I've got a tao tao 125 with a drive, neutral and reverse. Last week after it was rode for about 2 hours it wouldn't go forward reverse still worked. Put it up for about 2 days changed the oil then started working again. after about the second day my daughter was riding a few hours on and off it stopped again.If you lift up back tires they spin and if you hit the gas they'll spin faster. but if it's on the ground on pulls half speed in reverse and not at all forward. I would appreciate any help anyone could give.

Any solution to this??