Wow, tough day. Think I would of took to drink 
I donāt own a Pi, but thought I ask if it comes with mate-tweak? If so, pull it up (mate-tweak) and try changing panels. Could also see if changing the window manager (to compiz) will do anything. Again, if you have mate tweak.
Drankinās what got me in this mess in the first place. 
Protip: Donāt work on your comuter when you come home at bar thirty.
Tweak doesnāt seem to nothin either.
I would also try reinstalling mate-panel and mate-panel-common.
A fix all command that may also work on a Pi:
sudo apt -f installShould i āapt remove --purgeā or is there a reinstall command?
Think I just go with a reinstall command.
sudo apt install --reinstall mate-panel mate-panel-common
-f install say anything?
Nothing on -f install.
Rebooting to see what happens
I just discovered that i canāt change the settings for anything. I went to sound settings to turn off the obnoxious system sounds and though it gave me the option to turn them off, it stayed right there on Ubuntu.
And while the system sounds work, they dont work for applications.
All of your panel settings are stored in your /home directory. If you have placed /home in a different partition from the root/system directory, and your /etc/fstab has been corrupted somehow so your /home partition isnāt getting mounted over /home, then your panel icons and background and all the other settings youāve tweaked will just disappear until you get the mount situation ironed out.
Thereās also the possibility that you are using one of the earlier kernels. Of all the kernels that have come out of the repo since i installed ubuntu-mate, all those preceding the rev-70 kernel (and associated initramfs) have intermittently skipped some mounts from fstab on my xps13. I believe they might have fixed what appears to have been a systemd timing issue, but iāve only been running the rev-70 kernel for a day or two; it hasnāt been misbehaving like the rev-66 kernel and those before it were misbehaving on my xps13. I donāt know why everybody hasnāt been seeing skipped mounts, so iāve been attributing it to some xps13 peculiarity that drives out a timing bug in systemd, but without spending unconscionable amounts of time digging, i canāt say for sure what it was or even if itās stopped, i just havenāt seen evidence of the issue since i installed the rev-70 kernel.
If you have multiple userids set up, check the others; if itās a missing mount (however it got that way) they would also be messed up.
Maybe this isnāt the issue thatās causing the problem, but itās something to check imo. I donāt own a pi and know nothing about them. Good luck,
Also try:
sudo dpkg --configure -aThat didnāt work either.
Whats the hotkey for the main menu i was thinking i could try creating another user and seeing what happens when i log in there.
Crankypuss, thanks for replying but I understood exactly none of what you just wrote.
Excellent idea
Or just switch to your āguest sessionā if you have one.
Awesome. Whats the name of the program that does " users and groups" from alt- F2?
The command:
users-adminGuest session works perfectly. So what does that tell me?
Maybe your /.config need to reset, but why not just create a new user with admin (sudo) rights and use it.
I did create a new admin, but I would still like to know what happened to the original account.
Like I said, maybe ~/.config. I really donāt have anything to go on yet, so just a guess.
Can you compare the new and old /.config?
theres a lot of stuff in this folder. What am i looking for?
Donāt put too much into it, like I said, its just guess work.
But you are back to normal with a new user?
yeah im good, just need to move some stuff from the other account to this one.
So the solution was a work-a-round. Well done