Why wont my phone work?!?

Recently my phone stopped working for calls. I have an LG EnV3 and whenever i get calls i cant hear the person but they can hear me. I have checked and its not on mute. I have also checked for water damadge. Sometimes it does turn off for no reason or when im texting the screen just goes black. I dont know if that has anything to do with it but i hope you can help me figure out what's wrong with it.