Why have I got coloured vertical lines on my laptop screen?

It started off with just three or four vertical coloured lines and has now progressed to about a 2 inch 'band' of coloured vertical lines. If I press the screen they disappear but as soon as I release any pressure on the screen they return (sorry, I know I shouldnt be putting any pressure on the fragile screen but it was driving me nuts and if it means I get to see the full screen rather than only 3/4 then so be it until I can fix the problem).

Thanks.