I suspect when you "tried to free some space (by uninstall a app)" you might have removed a core part of the Ubuntu Desktop and accidentally triggered the removal of other desktop components. I know because I've made the same mistake myself.
Try this:
sudo apt install --reinstall ubuntu-session
I suspect when you "tried to free some space (by uninstall a app)" you might have removed a core part of the Ubuntu Desktop and accidentally triggered the removal of other desktop components. I know because I've made the same mistake myself.
Try this:
sudo apt install --reinstall ubuntu-session