I had a FM transmitter plugged into my phone in the car earlier and was using the iPod function, it was working fine. After I'd got out of the car and disconnected it, now sound only works when the earbuds are connected. There is no lock sound, no iPod sound, no game sound. It DOES work in headphones though.

I have tried rebooting it to no avail. I have checked the volume levels. I assume it's stuck thinking that headphones are plugged into it so it won't issue sound through the speakers. I tried blowing into the headphone port with an airduster but that didn't solve it.

I noticed that when the earbuds are connected the volume control is back but when disconnected the volume bar disappears.

Does anyone know how I can stop it from thinking that headphones are plugged in and get sound back (assuming that's the cause)?

Souns like the phone is in "Airplane Mode" or something similar. Try changing the profile.

My brother had the same problem and a simple restart fixed it. Just hold the home button and the power button and slide to power off. Then press the power button again to start it back up. That should fix it.