Overdrive not working?

I just did a little offroading in my 96 2wd automatic and when i got back on the highway to go home it wouldnt shift into 4th and it felt very sluggish. I just went through some shallow mud holes and did some dirt burn outs and stuff, just as much as a 2wd w/bald tires can do.
Anyway, I cant find a button that takes overdrive off and on but I hope there is one that I accidentally pressed or something. Any help is much appreciated. Thanks, Ian

BTW: 45 for me is usually ~1200 and 55 is i guess 1500rpms and now its like 2000rpms for 55 or something. 4.0 I6 w/low gear ratio i guess.

nss probably got wet inside

it works now, i drove it to school right after i typed that