Engine revs, quad never goes faster than 10mph??

This is a JD Buck but thanks to The Googles I have discovered it is just a Bombardier Traxter with JD stickers on it.
I cannot find a single dealer or service shop in my area that will touch this so I am hoping to get some advice before I decide if this thing is scrap or repairable.

So I thought it would be fun to ride around in the snow.. Well after about 15 mins I noticed that the engine was reving way higher than the speed warranted.

I can put it into HL and R but it just barely crawled. I assume I burnt something out inside the transmission but the few people that I could get to even talk to me at local shops gave me horror stories about how it's going to cost more to repair than buy a new quad.

Now that it has sat the rest of the winter..
So, at this point it won't start, the starter just whirs, so time for new starter?

Once I can get it started, what can I look at to maybe repair this? Is there a trans rebuild kit? Are there maybe just some shredded belts or something inside the tranny?

Any suggestions or thoughts are greatly appreciated, if I can fix this for a couple hundred, or less, it will deff be cheaper than buying a whole new quad.