Chevy 2500 hd deisel not shifting?

Ok here's what's up..2004 chevy deisel truck..4wd..it's my cousins truck and had been sitting for about 3-4 months while he's out of town..I went to start it the other day and the battery's were DEAD...I replaced both if em and got the truck to run..I was ginna drive it tonight but it wouldn't shift out of either first or 2nd gear (I'm not sure which)...also the fuel gauge was reading nothing at all..and the part of the cluster that tells you what gear ur in wasn't lighting up at all..I wanna get it figured out before ge gets back in town do he don't have to worry about it..any info anyone would have I'd really appreciate it