factory reset ubuntu without losing data

Try configuring unconfigured packages:

sudo dpkg --configure -a
Update the contents of the repositories

sudo apt-get update
Try to fix missing dependencies:

sudo apt-get -f install
Update all packages with new versions available:

sudo apt-get full-upgrade
Reinstall Ubuntu desktop:

sudo apt-get install --reinstall ubuntu-desktop
Remove unnecessary packages:

sudo apt-get autoremove
Delete downloaded packages already installed:

sudo apt-get clean
Reboot the system to see if the issue was resolved:

sudo reboot