Command-A stopped working

scott723 wrote:

My 'Command-A' action has suddenly stopped working. Command C+V still work so i know that the Commend button is not faulty. Cannot even 'Select All' from the Edit drop bar

Reboot your Mac and test.

Restore defaults(?)

Use macOS keyboard shortcuts - Apple Support

If no resolve to trouble shoot further you can:

—Try a SafeBoot https://support.apple.com/en-us/HT201262

Takes noticeable longer to get to the login screen, does a 5 minute disk repair before it fully boots up, and certain system caches get cleared and rebuilt, including dynamic loader cache, etc.

Login and test. Reboot as normal and test. Caches get rebuilt automatically.

In Safe mode third party system modifications and system accelerations are disabled, it removes malware, etc hampering smooth operation, however a reboot will put it back to normal mode.

This test will tell you if third party interference; extensions etc are not loaded in safe boot mode.

—Test issue in another user (or guest user) account https://support.apple.com/guide/mac-help/set-up-other-users-on-your-mac-mtusr001/mac

This will tell you if it a universal issue or isolated to your user/admin account. 

Uninstall all third party apps that are Cleaners/Optimizers/VPN/Anti-Virus

Sometimes it's just weird. On my old late 2013 MBP the delete key would periodically stop working by itself and I would have to push the shift key along with it. and this just as suddenly, it would work again. I could find no one to tell me what was happening.