why will my car turn over but wont start...it had low oil but was not empty and it overheated twice?

i was told by someone that my engine was locked up but i dont believe that was true bc he put 2 qts of oil in it and it showed on the dipstick to be more than half full...so they checked my battery and i needed a new one...they put a new one on it and it still wouldnt start...it acts like it wants to start it just wont...im just tired of getting the run around and i was wondering if maybe yall could think of an idea of what is wrong with it...the more i know the better i will feel thanks :)