Won't start; Zero compression

Hi,  I have a 97 GTI with a 2.0 SOHC. I had replaced the timing belt 6 months ago. It has been running great until today. It quit and won't start. I have spark, and fuel, but zero compression on all 4 cyl. I verified the timing belt was intact and the CAM gear  marking and the flywheel marking are dead on as the day I installed it.

I am puzzled by zero compression on all 4. I took the vlave cover off, and all the lifters are operating. I assume I have bent valves or the head cracked. The car did not over heat and has the proper amount of coolant. The engine has 140k on it. I assume I'd be money ahead finding a low mileage used rather than the reapairing the head.

Any ideas on the zero compression?

Thanks

Doug