April 28, 2018 I upgraded to Ubuntu 18.04 and everything worked fine. Now, I don't know why I can't get into Nautilus. When I click the Files icon in the dock it starts to load but nothing launches.
I also can't get into the terminal (neither with Ctrl+Alt+T nor with the terminal icon). I don't know if the two problems are related, but they started to happen at the same time.
Edit 1: Rolled up from answer that should be in question, the Nautilus problem was (partially) solved:
I managed to open nautilus from Konsole and now it seems to work fine
(I can open it through the dock). However, when I close the Konsole,
it fails again.
Best Answer
About the "Shortcut Keys don't work" part.. I had a simmilar issue after upgrading to Ubuntu 18.04 : - Ctrl+Alt+T didn't work - lock screen ( Ctrl+Alt+L ) didn't work - media keys didn't work
Here is what worked for me:
At this point the shortcuts started to work again.
Hope this helps somebody.