1997 Chevy Cavalier Help!

I was driving 45mph down the road and all of a sudden my car came to a complete stop, Before I left the house I checked my trani fluid and it was full. I checked it because my car wouldnt back up. After my car got towed then impounded I got it home and I checked and the fluids are all still full. My shifter does not want to go into park so I have t slam it into park its not like I have to worrie about my car rolling anywhere because its completely stuck they had to use soap to get it off the flat bed. Please let me know what you think im so stuck and this is my only car Thanks so much ~Jess~