I have a 1998 pontiac grand am gt that runs but does not drive in first gear - just second and third, but not the over drive either. What could this be?

Your transmission probably lost first gear. Based on reliability ratings the 1998 Pontiac Grand Am is not notorious for transmission issues, but it seems like if you lost first gear that's what it is. It's going to be expensive, but you're going to have to rebuild/replace the transmission, as it seems like the only way to fix it.