I have a jailbroken iPhone 5s on 8.1.2. (B440).
My son (for whatever reason/long story) has deleted the music icon/app from the home screen. He did this from the main filesystem thinking he could copy it to pc then put it back… he can't!
Further, I have tried to restore the phone using my back-up and by using my 8.1.2. ipsw but it wont work. I get errors saying e.g. firmware file is not compatible or cannot read library .itl as it was created by a newer version of iTunes. I've also tried restoring via basic recovery mode and DFU mode but get errors as above.