System File Checker (SFC) is a built-in Windows utility tool that is used to scan and repair corrupted or missing system files, including .DLL files. You must open the Command Prompt (cmd) as an Administrator to use this feature.
If you come across a file with the extension "filename.DL_" on your computer, dont be alarmed. This is a compressed backup version of a .dll file. To access the actual .dll file, you can use software like 7zip to extract it. Once extracted, you can proceed with its installation or use as needed.