No connection to computer, under dash or under hood.

Jumper started a car, a few weeks later started loosing power on freeway and began to run rough, let it sit a few days went to start it and battery was dead. Put charger on it fired it up and car ran smooth. A few weeks later my speedo went and my abs, asr and brakes low lights went on. Tried to get codes. No read out says no connection. Check fuses under hood, all ok. Need help. Will another computer from same model and same #s on computer work? Does it need to get programmed? Or just disconnect batt, and replace computer?