No service: Are you getting any signal [bars]? If not then what networks do you see when you manually scan for networks? Can you see/connect to 48 or O2 if 48 is not listed? If not then what happens? Has anything changed on your phone - e.g. software update? Can you use any services at all? What does your online account say about your membership status? Any chance you breached the fair usage limits and got barred?
Internet: did you ever configure your internet/APN settings? This is required for internet access to work: