You aren't giving us much to go on, but...
1. Reboot your PC twice to allow any partly completed Windows Updates to complete. Try MC again. If no go;
2. Reinstall MC26.0.47 over the top of the existing install. Try MC again. If no go;
3. Use the Win+R shortcut to open Windows Run dialogue, enter mc26.exe and press enter. If that works, check the desktop shortcut you are using to make sure it is correct. Fix it is necessary. Try MC again. If no go;
4. Do a normal uninstall including Registry entries and Library files (I assume and hope you have a recent Library Backup to Restore later - check that before uninstalling).
a. Reinstall MC26.0.47 and do not Restore the Library. Does MC run now? It should because it is just a basic installation.
b. If MC did run okay, Restore your Library Backup without Settings. Still okay?
c. If still okay, Restore Library Backup with Settings. Still okay? If no go;
5. Uninstall MC26 again, including Registry entries and Library files.
a. Install MC26.0.20. Does that work? If it works;
b. Install MC26.0.47. Does that work? If it works;
C. If MC did run okay, Restore your Library Backup without Settings. Still okay?
d. If still okay, Restore Library Backup with Settings. Still okay? If no go;
6. Try to run MC and then look in the Windows Event Viewer. Anything obvious? Any attempt to start MC?
Report back if you get this far without it working. What worked, what didn't?