Files and folders to delete to restore plasma to default config

I've got Kubuntu 22.04 on this dinosaur with Plasma 5.24.7.  A few 
months ago it started acting up.  First it wouldn't play the startup 
sound that it previously played.  Then it stopped playing the logout 
sound.  Then it started taking a log time to show the desktop after 
logging in.  One day last month, I when I logged in, all I got was a 
black screen with a mouse pointer.  Ctrl alt backspace got me  back to 
the login screen, but when I tried, all I got was the black screen with 
the mouse pointer.  Rebooting didn't fix this.  Eventually I found a 
forum online where someone had the same problem and fixed it by multiple 
files and folders under .config and .local.  He logged in and got the 
default setup.  I tried this and got the default setup also.  Once I 
reconfigured  the login and logout sounds, it played them again. Now 
it's starting again.  This week it stopped playing the logout sound.

What file and folders do I need to delete to return to the default 
configuration?   I know I said the person in another forum said he 
deleted a bunch of stuff and got back to the default setup, but he said 
he wasn't sure which of those files and folders needed to be deleted.  
I'd like to find out just what needs to be deleted to go back to the 
default config so I can delete only what needs to be deleted, recreate 
the setup I want, then back it up so I can replace those files when it 
messes up again

thanks