Problem with earphone.

firstly u check that your headphone is an original one provided by motorola.many duplicate headphone does not support all phones. if it is original check that your headphone pin is inserted properly in your phone.if it dosen't work then also it is a advice to change your headphone your headphone would have got damaged.
second ans
try not to keep larger size themes. do not overload your phone memory try to keep atleast 7-8 mb free memory of your phone.
if it does not process fast then install antivirus software and scan your your phone it may be infected with virus