What should I do if the required DLL file is missing or deleted from my Windows 7 system?

If a required DLL file is missing: 1. **Reinstall the application:** This is the safest and most recommended method, as it ensures the correct version of the DLL is installed along with its dependencies. 2. **Copy from another computer:** If you have another Windows 7 computer running the same software and OS version, you can copy the DLL from `C:\Windows\System32` (or `C:\Windows\SysWOW64` for 64-bit systems running 32-bit apps) to the problematic system. Be extremely cautious, as using incorrect versions can cause more problems. 3. **System Restore:** If the file was recently deleted, you might be able to revert your system to a previous state when the file was present. 4. **Run System File Checker (SFC):** Open Command Prompt as administrator and type `sfc /scannow`. This will scan for and attempt to repair corrupted or missing Windows system files, including some crucial DLLs.