It wouldn't engage into any gears but park

One night after diving my car though town I went to park it for the night. The next morning when I was leaving for work it wouldn't engage into any gears but park. It has not given me any indications of problems before this happened. When I try to put it in to gear it bogs the motor down slightly then revs back up after a few seconds but will not move. When its in any of the gears it will move freely when pushed and will lock down when in park. I had a friend tell me to check "the sensor". Any ideas?