Do you mean the program itself can’t run or that you cannot launch any games. If you mean the former, make sure you’re trying to run citra-qt.exe and not citra.exe. If you can’t launch citra-qt.exe, try adding citra-qt.exe as an exception to your virusscanner.
If it still doesn’t launch, type winver into your search bar and launch the pompt when it comes up. This should give you information about your windows installation and update version. If you’re on Windows 10 version 1909, you’ll need to update to a newer windows version (2004/20H2/21H2). We’ve had some reports of users being unable to launch Citra on that Windows 10 version 1909 for some unknown reason.
The file extensions are hidden by default sometimes. You can enable them by opening File explorer and going to the View tab and enable File name extensions
As for your crash, maybe there are some corrupt Windows files. Follow the steps below to check for that:
Type cmd into your search bar, then right click it when it pops up and select Run as administrator
After that’s done doing it’s thing, restart your PC (Start → Restart) and see if you can launch citra-qt.exe now.
If that doesn’t work, open up the command prompt (cmd.exe) as an administrator again, type in DISM /Online /Cleanup-Image /RestoreHealth:
Press the Enter key and wait until it’s done, then reboot your PC once gain (Start → Restart). Now run the command prompt (cmd.exe) as administrator one last time and do another sfc /scannow, followed by a reboot once more (Start → Restart).
Now test citra-qt.exe.