98 k1500 won't move and 4wd lights are off

[stikxs]

So got a 98 that has been doing a lot of sitting in recent years, drove about 10 miles a couple months ago but other than that a lot of sitting. I just went out to try and move it in the driveway and it started fine and went into drive and i pulled forward maybe 20ft or so then stopped and shifted to reverse. Heard a clunk sound from the rear somewhere and now the truck won't move after getting into reverse. I can shift through gears fine, and when in drive or reverse if i give it gas it nudges a little but won't move, like if you're holding the brake (kinda raises up like when doing a burnout). It also will not roll when put in neutral. I did notice the 2/4wd button lights were not lit up, i don't think they did at all today. Any ideas where to start looking?