Hey Ste-v, I don't know if I can help you but I would suggest if you are looking for advice that you may want to put way more information in your post that just 'not printing'
Maybe add Brand of Printer, Model, type of software (version number), how old is the printer? did it just happen? did you just change a head and it stopped printing?
You know, like going to a doctor. You don't just walk in and say 'need help', you sorta have to expound a little bit. Just sayin'