Please help

First its not a HOnda but seek help immediately.

I have a 1997 Mazda 626 4 cyl.

I just had the timing belt/ and timing tensioner changed.
I paid the man, took the car and was getting some slight pinging. Went pay,
the turn the distributer about an inch and things were fine. Came home when
for run later that day and the no compression.....no power....spuddering.

Went back to mechanic had compression test done and the results were.....175
on cylinders 1 and 2.....and 25 on 3 and 4.
He tells me the head gasket is gone between those two valves low on
compression.

My question is would have it jumped the timing....and if so would this cost
the low compression in 3 and 4 cylinder?
its strange to me the car was fine then just as I have the belt changed this
happens.

Please help
thanks