[Q] at&t htc one m8 rom question topic

I backed up my phone and have had troubles restoring a rom, although I don't have access to it at the moment, if I restore a backup I made with htc sync manager will it restore the rom I had? and if not, I've had troubles installing a rom with a .zip, because every rom I find is for a different bootloader (I have 1.6) and .exe's fail because my bootloader is unlocked. if I relock it should the .exe work regardless of the bootloader version. if neither of these would work, what do you suggest I do? I'd send it in to htc but they estimated 0, then another person said 0 is average, but it could be up to 0 just to fix it, and at that price I could almost buy another (sorry if these are easy questions)