Car stopped while driving

Ok so my car stopped while i was driving and now it wont turn over. Before it stopped i noticed the oil light was on and to tell you the truth i honestly dont remember the last time i had the oil changed. I took the car to a mechanic who did not put the car on the computer...he only took the lid off of the engine and said the compressor was low and that something was wrong with the timing belt and that there wasnt any oil in the engine. he also placed some type of small gadget inside of the car which said there was a problem with the timing belt. However today he's saying the belt is fine and that its only the engine thats messed up. I know he could be accurate but wouldnt my car give me a sign other than the oil light? My car never ran hot or smoked and i didnt hear any knocking in the motor at all and i never smelled any gas or anything like that....how accurate do you think this mechanic is? I honestly feel like he's trying to get over on me