HELP!!! work colleague "bricked" my iphone!

hello,

I have an apple iPhone 5S, while i was in work a work colleague though they would do the 1st January 1970 trick on my phone not knowing what would happen, my phone is only 9-10 months old and just wondering if i can be fixed or is their anything i can do as its just loading the apple logo constantly and im not sure what happen to it other than what I've been told, am i going to need to buy a new phone or can it be fixed?

Many thanks

Stephanie Nock.