Reboot your Frozen Linux based system

Ctrl-Alt-Backspace doesn't work ?

Try this

Hold down the Alt and SysRq (Print Screen) keys.

While holding those down, type the following in order. Nothing will appear to happen until the last letter is pressed: REISUB

Watch your computer reboot magically.

What the individual keys do in that sequence are not as important as what it does as a whole: stops all programs, unmounts all drives, and reboots.

To remember this,

Raising Skinny Elephants Is Utterly Boring or R E I S U B - is just the word busier in reverse.

R gives back control of the keyboard
S issues a sync
E sends all processes but init the term singal
I sends all processes but init the kill signal
U mounts all filesystem ro to prevent a fsck at reboot
B reboots the system

Via Fosswire