I haven't had the engine fired up for about three months and went to try and start it this afternoon and it won't fire up. I've checked all the plugs and i'm getting a spark on them, had the injectors out and i'm getting a nice spray of fuel when i crank the engine, but its not even trying to fire. The engine just keeps turning over.

The engine has been untouched since it last ran. The only thing that i can see is different is that when i set piston 1 to tdc last time the rotor arm was pointing towards the 2 o'clock position and when i checked it today, it ended up in the 4 o'clock position with piston 1 at tdc. Could it be that the cambelt might have jumped? And if so how do i sort it out?