No Sound when earphones are NOT plugged in.

Hello, I have a 2006 Macbook Pro A1181. No sound. I plug in earphones and I have sound. The sound controls on the key board (F12 ) only work when earphones are plugged in. Person stated that it MAY have started when they tried to plug in earphones in wrong hole (not sure if that mattered). Any ideas of what could be the problem?

Thanks for the response. It not showing anything for internal speakers. I went to "system preferences" ----> "Sound"----> "output" and the only thing listed is Name: Digital Out and Type: Optical digital-out port

Any other ideas?