Close of the frozen LINUX Ubuntu
Keep pressing "alt" and "Print Screen"
and press R -> S -> E -> I -> U -> O
> "alt" + "Print Screen" + R + S + E + I + U + O
Restarting the frozen LINUX Ubuntu
Almost the same as the close.
Only the last key is different.
> "alt" + "Print Screen" + R + S + E + I + U + B