Last night i was idling while checking out the street directory, and my lpg just cut out as clean as if i had turned it off, now wont go at all on LPG will crank but thats it wont fire at all, still runs great on petrol but not the point, still have 2/3 of a tank of gas, any ideas? will take photos of what people need to see for ideas i just dont know what i should photograph

I'd be checking power to the lockoff first of all.

I'm guessing it starts on petrol so you'll have to get a test light or multi meter on the terminal and get someone to switch to LPG as you do it.... Also keep your finger on the lockoff and see if you feel it click when it switches over, you should be able to hear it but feel is always good. If there is power and the solenoid doesn't click then it could be stuffed.

Otherwise it would be a computer or module causing the problem, check all your wiring connections aswell, something might have jumped off.

You'll most likely have 2 lockoffs - one at the tank and the other at the converter - be sure you check both.
There should also be a separate black box which is a safety cutout, this may also be playing up.
Judging what you've said, it certainly sounds like the lockoffs are shutting gas off.

funny thing is its worked today without a hitch

Check your water level, convertor could be freezing up too