Depending on the version of Windows you're using, there are several different ways to automatically repair major Windows operating system problems without resorting to a destructive process, like a Reset Your PC or a Windows Clean Install.
The newest versions of Windows have really easy, automated ways of repairing problems that you might have tried to fix manually but were unsuccessful at, like random error messages, overall slowness, even problems that prevent Windows from starting at all.
It's a mixed bag with older versions of Windows, with some automatic repairs for certain types of issues or all-or-nothing repair processes that, while sometimes might seem like overkill, are certainly welcome when you need them.
"How Do I Automatically Repair Windows Problems?"
Most of the time, especially when a major problem is occurring, the best way to automatically repair Windows is to boot from recovery media, or the original Windows setup media, and choosing the correct diagnostic option.
The specific steps involved in performing a Startup Repair, a Repair Install, or a Refresh Your PC can differ considerably depending on the operating system used.
Important: Please don't use what you read below as the only troubleshooting for your problem. Sometimes the ideas below are the best bet, but other times there are much more simple and effective solutions. So, if you haven't already, search through my site for the specific error message or behavior that you're seeing - I might have much more specific advice to give.
Automatically Repair Windows 8
Windows 8 has the greatest number of automatic repair options, which is no surprise considering that it's the newest version of the Microsoft Windows family.
A Startup Repair (formerly called Automatic Repair) is your best bet if Windows 8 isn't starting correctly. Startup Repair is available from the Advanced Startup Options menu.
See How to Access Advanced Startup Options for instructions on accessing that menu.
If an Startup Repair didn't do the trick, or the problem you're trying to fix isn't related to Windows 8 starting properly, a Refresh Your PC is your next best bet. This is like a "copy over" of Windows and, if you're familiar with Windows XP, is very similar to the Repair Install process in that operating system.
See How to Refresh Your PC in Windows 8 for a tutorial on this process. None of your saved data is destroyed during this process.
Automatically Repair Windows 7 or Windows Vista
Windows 7 and Windows Vista have nearly identical processes for automatically repairing important files. This process is called Startup Repair and functions similarly to the Startup Repair in Windows 8 in that it only fixes problems related to Windows starting properly.
Unfortunately, there is nothing like Refresh Your PC (Windows 8) or a Repair Install (Windows XP) that works to overwrite all important files, processes that tend to be very helpful when you have particularly stubborn problems in Windows but don't want to lose your important data.
Automatically Repair Windows XP
Windows XP really only has one automatic repair process, called the Repair Install.
The Repair Install process is very similar to the Refresh Your PC process in Windows 8 in that it overwrites all of the important files in Windows XP in an attempt to fix whatever might ail your computer.
See How to Repair Install Windows XP for a complete walkthrough.
Important: While the Repair Install process in Windows XP is not designed to remove any files, I recommend that you play it safe by backing up your important files. You should also prepare to reinstall your programs just in case the Repair Install damages any of their installations.
Having Trouble Repairing Windows?
Having trouble with one of the repair processes above? See Get More Help for information about contacting me for more help on social networks or via email, posting on tech support forums, and more.
Tip: If you're using a restore disc from your computer manufacturer instead of original Windows media or a system repair or recovery disc/drive, the automatic repair processes as described in the linked tutorials above may not be possible. In your case, please reference the documentation that came with your computer or contact your computer manufacturer directly for directions.