Loss of power, very rough idle in punto

[freemo77]

Asking on behalf of a friend as tonight we got stranded in not particulary the nicest of areas as his car broke down on our way into town

The best way to describe it would be that we were driving along, all seemed fine and then there was a loud knocking noise and a huge loss in power

At this point we pulled over and turned the car off, on starting it again it struggled to start, but it did but the idle seemed very rough and would drop right down to a point where it would sound like it was stalling

If anyone could share any light on the matter it would be much appreciated

 

[Toms_clio]

Its a punto!!
Headgasket!