DVD

I just bought a used DVD Player and when I play a DVD, it starts out fine, then during play, it will freeze the screen and sometimes continue after 30 or so seconds, but skips the chapter it was on. Other times it freezes and never comes back around, but you can see it shuffling through the chapters. Can you maybe tell me if this might be an easy fix, or am I wasting my time?

Thank You,
DJ