Mfplat.dll errors are caused by situations that lead to the removal or corruption of the mfplat DLL file. This file is part of Microsoft's Media Foundation Platform. Not all versions of Windows have it installed, which could be a reason for the file being missing.
How to Fix Missing Mfplat dll File on Windows 10
Follow these steps in the order they are listed below to try the simpler solutions first.
Recover mfplat.dll from Recycle Bin. The simplest possible cause of a "missing" mfplat.dll file is that you accidentally deleted it.
If you suspect this, but you've already emptied the Recycle Bin, you may be able to recover the file with a free data recovery program. However, this is only a good idea if you're certain that you deleted the file yourself and that it was working fine before you did so.