Only top half of screen has picture there is a white line through the centre and bottom half black

Good day to you friend. you have a vertical problem. when you go into your set the first place you need to look is in the vertical circuits check your size and linear adjustments. be careful because these are sensitive. you want to slowly and carefully do adjustments. check your transistors, bias resistors, diodes, and possibly capacitors. if you cannot find the culprit there, then replace the vertical output ic. thank you for your time and please rate my solution.

If this is a conventional TV with the original style Cathode Ray tube, this fault sounds like failure of the LINE OUTPUT TRANSFORMER.
It can be fixed, but may cost you around £70 ($120), possibly more if you have to call out an engineer.
Best NOT to use the TV as it is, because it will certainly damage the tube if you leave it running with that white line through the centre!!!
If you do use it, this line will become permanent and if you get the TV fixed later, there will always be a burnt section of the screen where the white line was - so I suggest you either pay to get it fixed right away, or consider buying a replacement.