@tomn
In the past I hit the keyboard "A" key or the "A" key on my wired Xbox one controller and that launched the screen with the games.
You don't need to press any button to start Emulationstation (the interface that lets you choose between different consoles/games), so if you needed to, something was already wrong.
1 - Your problem may be in the SD card, which may have corrupted, with the help of a USB adapter, try to check the errors through Windows, it may solve.
2 - Or, check if the problem is not just with the emulationstation:
Start your Rpi4 until you reach this screen
on a computer or smartphone, open a browser (could be Chrome or Firefox, etc.)
in your browser's address bar, type:
recalbox/help
This will open the Recalbox manager.
There is a part with Stop and Restart EmulationStation options
Click on Restart ES, and wait a few seconds
Emulationstation should start after that. I recommend that after ES starts you do a factory reset (available through advanced settings), just in case (you will keep all your personal files, but lose all custom settings).
3 - If that doesn't work, you may have to follow this procedure (enable subtitles):
https://www.youtube.com/watch?v=skeULeTu7p8&list=PL2oNQ0AT7fx2ExiSNrfHUzga5GnogI4sh&index=24&ab_channel=Recalbox
If none of this resolves, I recommend you to change the SD card, original and class 10 SD cards are recommended, ideally keep the system on an SD card, and personal files on an external device (as mentioned in video).
