going into gear but is not catching the gear enabling it to move.

What is your question?

My car was stolen 9 days ago, it was found 300 miles from home and is disabled according to the impound lot, they have said that it's able to go into gear But does not seem to be "catching" the gear after it is put in not enabling the car to be moved. What could be causing this problem? I had this problem once or twice after buying the car and putting it in first gear, but after shutting it down and restarting it was able to be put into gear and ran normally. We had it hooked up to a sensor at a local garage which gave us some codes but those all indicated a problem with the O2 sensor and as far as before the theft of my vehicle there was not any major problems with shifting, starting, or moving the car. I'm afraid that the man whole stole it did serious damage, any opinions?