2000 Holden Commodore car wont start

If this just happened over night then we can assume safely that the compression is not the issue. So that leaves spark, fuel, and air.

We need to know how you checked for fuel because this is the most likely issue. If all you did was check the rail for pressure from fuel squirting out of the Schrader valve then that is not going to be good enough to make sure the pressure is good enough to start the engine

Here are a couple guides that will help with this issue and checking the pressure:

https://youtu.be/dCjmRL3p4Cs

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Then we need to remove a spark plug and hold it against the block and make sure the engine has spark. If it has fuel pressure and spark then we can move on, however, I highly suspect this is a fuel issue.

The easiest way to confirm this is to spray starter fluid in the intake and crank the engine and see if it starts. If it does then it is a fuel issue.

Also we should check for codes and see if there is anything that points us in the better direction.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please run through this info and let us know what questions you have. Thanks