from a working pc, download "PartedMagic" and create either a bootable USB or CD with it.
with the bootable USB, plug it into a usb port of hte corrupt pc, power up the pc and press F12 at or during BIOS screen, select BOOT OPTIONS, you should see the USB, it might not say Parted Magic but should say the model/make of the USB, arrow to it and hit enter, you should now see Parted Magic start to load, it might ask you what kind of keyboard and couple other questions in boot up, the default answers usually work without issue. Once you're in Parted Magic OS, you should be able to mount the C drive, open it and save any data you want from it - you'll need another USB or external drive or uncorrupt internal drive to copy the data to - don' t...