0 compression after head gasket n water pump repair

I have an 01 Chrysler Sebring 2.7 v6. A few weeks ago, car died n I found water in oil. Car would start but would die shortly after. I changed head gasket along with water pump. I also had cylinder head checked and it was fine. I go to start car and now it won't start. I have 0 compression. Here's a few questions:
1. I hear because the timing is off that's why there's 0 compression, true or false?
2. I hear I am not at risk of bending valves since car won't start, true or false?
3. Is all this cause timing is off? I changed water pump n prior to this repair car started. My mechanic was paid n here I am trying to figure it out cause he never came back. All I can think of is timing must be wrong but why 0 compression on all cylinders. It won't ever start!