Restore Iphone 4s

My Iphone 4 screen got shattered, so I took my phone to my phone company and had them switch my service to my old android until I could afford to get the screen fixed, once I got the screen fixed i took both phones back in to have the service switched back, and they told me the serial numbers didn't match, but the phone still had all of my messages and pictures, so they messed with it and tried updating it and it got put into recovery mode and they couldnt get it out, so i hooked it up to my itunes and it went through the whole extracting software thing and then a pop-up came up that said "the Iphone could not be updated, device not found" what do i do?!