I have no pain but can't hear normally now from left ear. could it be a perforated eardrum?

See an ENT: Either have your family doctor examine you, and if deemed necessary they will refer you to an ENT doctor for further management.

Need more info: Hearing loss can be from many causes: barotrauma, trauma, eustachean tube dysfunction, acoustic neuroma, and yea even perf drum to name a few. Time of onset, rapid? Slow? Allergies? Recent cold? Recent concert? You should have thorough history taken and physical exam by your physician.