Hello all, I'm new to the site but I was wondering if you have anyone on here who could help me with a problem I have with my tv?

I switched tv's for about a week because I broke the remote control for my usual tv and I had to watch the portable for a week.
When I got my replacement remote control I reverted back to my main tv, but there is now a problem with the picture that I have been unable to solve.
The problem is that the top and bottom of the picture is missing. I've tried every setting on the tv, zoom, full picture etc, but I can't cure it.
A friend suggested that it may be something to do with Sky, but I've been through the digibox and tried every picture setting on Sky and it doesn't solve the problem.
I've even bypassed the Skybox and plugged the aerial directly into the tv, and I stll can't solve it. The top and bottom of the picture is still missing in teletext mode too.

Apart from this, the tv seems to be working fine

Anyone got any ideas please?