Toyota Repair: No compression, compression gauge, head gasket

Question
1993 toyota pickup original engine 4 cylinder fuel injection 120,000 miles, automatic trans.  I started to all of a suden  to loose power, drove 150 miles and then I broke down.  Engine did not smoke at all, it ran well except for lack of power.  I checked the compression and there is no compression in any of the cylinders.  Timing chain is still on but could be a little tighter,  fuel is going to the engine.  Head gasket is fine as there is no water in the oil.

Answer
A total loss of compression is normally due to severe engine overheating, this will cause the cylinder walls to burn as well as the pistons and rings but I'm not so sure that is the case. When the engine is cranked over with the spark plugs in does it sound like it has compression or does it just turn over like the spark plugs are out?
If it sounds normal try using a different compression gauge and recheck it.
Although I have never seen it happen it's possible that the timing chain broke, this will cause the pistons to come up and bend the valves. By "no compression" do you mean that it is at absolute zero? Maybe a little more information would help me.