What’s wrong with my car?

I have a 2007 Chevrolet Avalanche truck, I was
driving down the highway and the RPMs flew up to
about 6000 (they never surpass 3500) so I pulled
over and called my dad to see what I should do, the
motor sounded like I was still driving at 6000 rpms
and that lasted for about five minutes, when I went
to pull back onto the highway to turn around and
take it home, it wouldn’t move in any gear (R, D, 3,
2, or 1). The gears shift but the drive shaft does not
move. Tranny fluid is super high which is odd
because we’ve never overfilled it, any one know
what’s wrong with her??