[samprix]

Well don't know what you have tried, but aside from obvious problems like rodent damage, ect. You may want to try holding down the accelerator, as if the engine is flooded. I know it sounds strange, but I had this happen to my Saturn. I had moved the car from the drive way into the garage on a cold motor. The car was only running for maybe 20 seconds. When a came back after a week's vacation the car wouldn't start because it was still flooded. I held the pedal to the floor while cranking and it finally sputtered to life and cleared out the excess and ran smooth. Worth a try.