The sfc /scannow command will scan all protected system files, and replace corrupted files with a cached copy that is located in a compressed folder at %WinDir%\System32\dllcache. The %WinDir% placeholder represents the Windows operating system folder.

Follow these steps to automatically diagnose and repair Windows security problems by turning on UAC, DEP protection, Windows Firewall, and other Windows security options and features. Select the Download button on this page.

System File Checker is a utility in Windows that checks for problems with files on your computer. To run it, follow these steps: Make sure you've installed the latest updates for Windows, and then restart your machine.

When you try to access or work with files and folders in Windows, you experience one or more of the following issues: Issue 1: You receive an "Access Denied" error message or a similar message. Issue 2: You cannot access, change, save, or delete files and folders.

Use this app to try to recover lost files that have been deleted from your local storage device (including internal drives, external drives, and USB devices) and can’t be restored from the Recycle Bin.

This article describes an issue that occurs when you try to display a user's "effective access" to a file in Windows 8.1, Windows Server 2012 R2, Windows 8, or Windows Server 2012. You can resolve this issue for Windows 8.1 and Windows Server 2012 R2 by using the update in this article.

Symptoms. An application that is running on Windows 8 or Windows Server 2012 and that uses the StartDocPrinter API may encounter a problem in which the spooler deletes and re-creates the file that is specified in the pOutputFile pointer.

Restore deleted files and folders or restore a file or folder to a previous state. Navigate to the folder that used to contain the file or folder, right-click it, and then select Restore previous versions.

KB 3063843 contains a leak fix and a cleanup utility that removes leaked WNF state registrations. Such registrations cause delayed user logons on Windows 8.1 or Windows Server 2012 R2, or you receive "0x800705AA" error when you use an app.

Regsvr32 is a command-line utility to register and unregister OLE controls, such as DLLs and ActiveX controls in the Windows Registry. Regsvr32.exe is installed in the %systemroot%\System32 folder in Windows XP and later versions of Windows.