Hi Bigmamma! Whereabouts in the country are you? I'm in Yorkshire with Virgin and Channel 4 is fine here. I think you can go on the Virgin website and somewhere you should be able to find out if there is any maintenance going on in your area. Or alternatively if you give them a ring sometimes they have a recorded message before you put through to the 'report a fault' part of the centre which tells you of any faults in areas, I think you may get charged for this tho (normal call rate)
Have you tried re-setting your box, turning off at the wall for 40 secs etc..? Sorry I cant be of much help :o(
Hope you get it back soon!