Windows Startup Repair works by restoring damaged or missing system files. This resolves software-based problems that prevent the computer from booting normally. Startup Repair does not resolve hardware issues or remove viruses from a computer.
Startup Repair only restores system files. It does not act as a backup tool and does not restore any damaged user files, such as documents or pictures. Since it does not remove viruses, it does not prevent malware-related startup problems from occurring again in the future.
For problems that Startup Repair cannot resolve, Microsoft recommends using its System Recovery Options menu or contacting the computer's manufacturer. These system recovery options include limited hardware tests, restoring the computer to an earlier point in time and the ability to perform a factory restore on the computer. While a factory restore resolves all software issues, including malware, it erases all user data from the computer.
Windows 8 uses Startup Repair just as earlier versions of Windows do, but its Advanced System Options offers different tools. Refresh Your PC is a new tool that allows the user to reinstall Windows without damaging user files, thus retaining documents, pictures and other files on the computer. Restore Your PC is the more traditional restore option, but it erases all user data.