Hello Omar,
Thank you for posting your query in Microsoft Community Forum.
- Did you make any specific change in the computer prior to getting the missing file error?
Mpclient.dll is a Client Interfacing module belonging to Microsoft Corporation’s Windows Defender. Windows Defender, previously known as Windows Anti-Spyware, is an anti-spyware application capable of scanning the user’s computer systems for a variety of malicious files, including viruses, malware and spyware; it also runs a number of other security features such as personal firewalling.
If you are using Windows Defender/Microsoft Security Essentials in your computer, then I would suggest you to uninstall and reinstall it and check if it works for you.
You may also run System File Checker tool to repair missing or corrupted system files.
Note: Do not close this Command Prompt window until the verification is 100% complete. The scan results will be shown after this process is finished.
After the process is finished, you may receive one of the following messages:
Windows Resource Protection did not find any integrity violations.
Windows Resource Protection could not perform the requested operation.
Windows Resource Protection found corrupt files and successfully repaired them.
Windows Resource Protection found corrupt files but was unable to fix some of them.
Hope this information is helpful. Please do let us know the result, we’ll be glad to assist you.
Thank you.