Heres the situation. I was riding out at Superstition Mountain near Octillo Wells. I was riding in a lot of Sand hills. Almost when we get to our destination "Sand Dam" I lay by 2004 Yam yz450f down kinda softly. All of a sudden I can't can shift and it stuck in like a 1st / 2nd gear and when I go to give some Throttle I High Rev and barely move. Later I'm stuck with no gear changing and have to get towed back to camp. When I get back I let it cool. After awhile I start it back up and its shifts into gear but it High revs and barely pulls. As in when I apply throttle in kinda starts pulling and gripping then I apply a little more and nothing. Just High Revs and barely goes. ??? Did I just go thru a Clutch and need to Plates or need some adjustment? Can anyone help me before I end spending too much money and get fix it cheaper? Anything to inspect? thanks.