I cant open Lightroom - System error - mfc140u.dll was not found. I looked online on how to fix it but nothing is working.

The mfc140u.dll is part of Microsoft Visual Studio. Can I suggest that reinstalling the Visual C packages would restore mfc140u.dll for you.

• In the Creative Cloud app, press CTRL + ALT + T (Win) to launch Creative Cloud Troubleshooter & select 'Close Creative Cloud and related processes' > click on Go.
• Go to 'Add or Remove programs' in Windows, search & find all the installations of Microsoft Visual C++ Redistributable (all years).
• Uninstall them completely. Even if there is an option to repair them, Uninstall all the existing MSVC++ packages.
• Download a fresh package of Latest Supported installers for MSVC++ from this link: . 
• https://learn.microsoft.com/en-us/cpp/windows/latest-supported-vc-redist
• Right-click the downloaded file and select Extract All.
• Reinstall all packages (32bit & 64bit) & then restart the computer.