2003 Chevy Express transmition won, t automaticly or manual

I got a 2003 express cargo van recently some body try to stold it and they boke the ignition swith so I replace it w a new one since then my transmition won't shift it will go fowar but feels like it get stok on one gear the transmiton automaticly or manual wiil not shift I wonder if I need to program the computer since I change the ignition swith or if there is a sensor that I need to check I don't know what it is I was tinking that the transmition was bad and I rebuild it but is doing the same thing do you know what I can do to fix thiis problem?