Hello, for some reason i lost reverse second and forth gear. Does anybody have any ideas?

Oh, it's a 1999 chevy silverado w/ a 5.3 vortec engine 4x4

I hit a bump and losted 3 gears??

And...1st gear is perfect (still does a burnout) but i have to wind the engine to about 4 grand, then it shifts into 3rd gear

 

The sunshell is stripped

 

I had this happen to my '83 Silverado. It had the 700R4, brand new with 38,000 miles on a factory replacement tranny. 2nd and 4th went completely out. The mechanic showed me the transmission once it was opened up on the jackstand. The bands that control the tension on those two gears run on a separate plane than 1st and 3rd. That is what broke, so an entire rebuild was in order.
Time to get out the checkbook!!! $$$