Your graphical interface has frozen, which happens when the desktop environment or display server stops responding to inputs while the kernel still tracks the mouse hardware.
Recover Using a Virtual Terminal
If your system is only partially frozen, you can switch to a text-based terminal to restart the desktop.
- Open a TTY: Press
Ctrl + Alt + F3(orF4/F5) to switch to a terminal screen. - Log in: Type your username and password when prompted (the password characters will not show as you type).
- Restart the display manager:
- For Ubuntu/GNOME:
sudo systemctl restart gdm - For KDE Plasma:
sudo systemctl restart sddm - For Linux Mint/XFCE:
sudo systemctl restart lightdm
- For Ubuntu/GNOME:
- Press Enter and enter your password if asked. This restarts your desktop environment.
Force Safe Reboot (Magic SysRq)
If the keyboard shortcuts and terminal do not work, your entire system kernel is locked. Use the safe REISUB shortcut instead of holding the power button.
NoteWhy REISUB is safer
Holding the power button cuts power immediately, risking filesystem corruption. REISUB steps through unmounting and syncing disks first, so the reboot is much less likely to damage your data.
- Hold down
AltandPrint Screen(SysRq) together. - While holding them, slowly press these keys one by one with a short pause in between:
R,E,I,S,U,B. - Your computer will safely sync disks, unmount filesystems, and reboot.