Forgot Pass Code

My iPhone 5 was stolen last year (police report filed). Recently, I received a call from a pawn shop indicating they had my phone (I sent texts using the 'Find My iPhone' app). Now, having my iPhone back, I am having difficulties accessing it as I had forgot my pass code. And, I cannot restore my a back-up as it is protected by the pass code. I've read the support articles on the Activation Lock feature of iOS7 to see if I can find a resolution to my problem, but I have not been successful. Please help!