It sounds to me as if your Operating System has been damaged beyond repair, and that you only option would be to re-install your system using the 'Return to Factory Settings' facility provided. Unfortunately, this would mean you would lose all you data, and, from what I can tell from your posting, you have not taken a back-up so you cannot repair your PC at present.
You first need to remove your heard drive and connect it to a working PC either as slave or in a caddy, and use this to copy all your data onto a new external device.
Once connected to another device, you could partition your Hard drive and copy your data into a second partition.
Once you have your data copied, return the HHD to your own PC and re-install your system from scratch.