my iphone 5 lost its firmware and IMEI. How do I get it back? I can't use the phone at all

I have an iphone 5 16gb. I think my latest updated version was 8.1.1. Dropped the phone once and all of a sudden, my signal was lost. THen i checked the firmware and its imei was gone. Tried fixing it with a technician and told me that its completely broken. Is it true? How do I fix this? I restarted it and connected it to my itunes and it keeps saying "there's a problem connecting your phone to itunes. Please try again later or contact Apple" . I cant use the phone at all! Please help me guys.