MFC140u.dll missing from my computer

When you searched your system did you find the file?

Is there no clue as to what this program is that is complaining about the missing file?

The mfc140u.dll is part of the Microsoft Visual Studio.

The files are not part of a standard Windows installation so no amount of Safe Mode, Clean Boot, System Repair or sfc /scannow is going to help (sorry Microsoft engaged Support Engineer alleged "experts").

Companies (or regular folks) that write programs to run on Windows platforms may use various and different versions of Visual C++ when they write their programs so you need to have the matching Redistributable files (Dynamic Linked Libraries) from Microsoft installed on your system so those programs can find what they need to run.

You don't need to install all the stuff for C++ - you just need the redistributable library files that come in a package of files you install.

Since you can't tell what version of Visual C++ different companies might be using, it is possible (and likely) that you are going to need different versions of the C++ Redistribuable library files installed on your system so if you look in your Add/Remove programs you might see several versions installed:

You can check your Add/Remove programs to see what you have installed now.

People often ask if they can uninstall the old versions and the answer is "maybe" since nobody but you knows what other programs you have installed that might be using the libraries from those old versions and if you uninstall them those program will not work anymore.

It is probably a good idea to have at least the latest version installed so visit this page and download install the right package for your systems architecture (32 or 64-bit):

https://support.microsoft.com/en-us/help/2977003/the-latest-supported-visual-c-downloads

You should also install this KB Update if it is not already installed (you can't install it twice):

https://support.microsoft.com/en-us/help/2999226/update-for-universal-c-runtime-in-windows

Depending on what program it is that is complaining you may have to download another version and install that too so you may have to check with the company that wrote the program that is complaining and ask them what you need.

When you get done you should be able to see something like this: