POWERED OFF MY PHONE AND LOST ALL CONTACTS...WTH?

i was having problems with facebook messenger today and decided to power off my iphone. when i powered it back on, ALL contacts that were stored are GONE!!!! what happened? I havent updated to ois6 yet...havent done a recent backup of my phone. Is this info gone forever or is there a way i can get the contacts back? LOVED MY PHONE UNTIL THIS HAPPENED!!!!