Before any repair is attempted, are your files safe? If not go get a current bootable CD/DVD of Linux Mint (folk tell me it's very much like Windows) and get your files out.

Now that your files are safe you can make a Windows 8 repair CD/DVD/USB. Here's a link about that.
https://neosmart.net/blog/2012/windows-8-recovery-disk-download/
Bob

PS. Our office got a recent Tosh. It allows us to create repair and restore media. Did you opt not to do that?