I recently received an iPhone 4S. I am new to iPhone usage. I bought a pair of earbuds to use with it. After I plugged them in the first time, when I unplug them the external speaker is not working. Is there something I can do to convince my iPhone that there ar no longer earphones plugged in? I have reset the phone several times by turning it off and on, blew into the earphone receptical, made sure the mute switch is not on. Please help!