Your C drive is in NTFS format, and DOS doesn't support NTFS format, so you can't access the contents of C drive in DOS. Now, in addition to reinstalling the system, you can also use the system disk to repair it, but this method is more troublesome. The best way is to remove the hard disk and put it in a normal machine to test the missing files in the corresponding folder. Don't try to convert NTFS into FAT32 format, which is very dangerous.