1997 Saturn SC2 clunks in reverse wont shift outa drive

hi i got a saturn sc2 and it was shifting fine then one day i noticed the serv engine light goin on and off then a few weeks later i was goin to back outa my driveway and the transmission clunked hard and now seems to be stuck in drive it wont shift gears anymore and theres no over drive also there is nothing there if i manually try to shift it,i changed the oil and still the same, it will shift to park ,reverse hard,and takes off in drive w no overdrive????