Question: how to fix mfplat.dll missing?
Answer: Restore mfplat. ... 
Install the Media Feature pack from Microsoft to restore the missing mfplat. ... 
Run a virus/malware scan of your entire system. ... 
Use System Restore to undo recent system changes. ... 
Run the sfc /scannow System File Checker command to replace a missing or corrupt copy of the mfplat.