System error that say The code execution cannot proceed because mfc140u.dll was not found.

This error is directly related to Microsoft Visual Studio. I see  no need to reinstall Lightroom 

Try these steps to manually recreate the MSVC++ Libraries:

•  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, please uninstall all the existing MSVC++ packages.
• Download a fresh package of installers for MSVC++ from this link:
  Latest Supported Visual C++ Redistributable Downloads | Microsoft Learn
• Right-click the downloaded files and select Extract All.
• Reinstall all packages (32-bit & 64-bit) one by one & then restart the computer once.