You should check this youtube tutorial: https://www.youtube.com/watch?v=pYjQePBR... Don't panic! As long as you can get into boot loader you should be fine!

Is your phone associated with your microsoft or exchange account? Maybe it automatically backed up your contacts.

This is really easy to fix! Download SoundAbout from app store and set 'phone call audio' to 'earpiece'. I experienced the problem after flashing CM12 lollipop rom on my GTI505, everything was fine at first and then suddendly audio during phone calls stopped working. Hope this will help future googlers :).