Samsung :: M540 - Calls Only Be Listened From Speaker Phone

I am posting on my friend's behalf as she is having phone troubles that started yesterday out of nowhere. During the day she was making / receiving phone calls fine and noticed no problems with her phone. However in the evening she took a call and couldn't hear anything until she turned on speaker phone. Since then we have not been able to get any phone calls to come out of the normal earpiece, just from the speaker. It almost seems as though it is a weird setting or something as the phone seems to be aware of the problem. Whenever she answers a call now it is immediately set to speaker phone when she hits the button to accept the call. If we then turn off speaker we can no longer hear the caller. I looked through all the settings and can't find anything. She assures me she never dropped the phone between the last normal call and the first time she had the problem.