How can I re-tune my tv? ?

I have a Bush tv LCD15TV009. I had to unplug it for a day or so and when I turned it back on all the channels had gone and when I try to auto tune it, it says it's busy and nothing happens. I'm using an outside aerial and I know that's not the problem because I can get Freeview via my DVD recorder using it. I've spoken to Bush who say the tv must've developed a fault but it was fine when I turned it off. They say it needs repairing. Does anyone know whether I can fix this myself, or what the problem is?