Hi Mugbatty,
I have the same problem with my Sony Bravia KDL32V4000. When the partial switchover happened we got the BBC channels OK. Then Border/ITV switchover kicked in and we re-tuned OK and got all channels. Then we went away for a week, came back and nothing! I have tried to retune at various points in the house and only get an error message indicating the aerial is not connected. However, when I set up a cheapo Aldi digibox and a portable on the same aerial feeds, everything works fine and dandy. I am not a happy bunny, as the Sony is the most expensive TV I have ever bought and it isn't working. Sony offer a telephone help line, but it's Mon to Fri from 9 a.m. to 5 p.m. exactly when I am at work and not at home. If you ask me, it's all a big fizzing con!
Have just read some more stuff. Try this thread - it may help: Pano DMR-EH60D switchover problem
Update: Have switched off at mains and left off for 30 mins. Came back, switched back on & rescanned digital and analogue - result - Nothing, Zero, Zilch. It looks like my dear little Sony is going back for a refund, as it is utterly unfit for purpose
Good luck with yours.
Houlie