If your TV is LCD this are the procedure/steps to fix your problem.
Half picture on top of the screen, and the bottom half is black
it means the back-light of your TV on the bottom is not working. This are the step on how to find the trouble of your TV:
First, you have to remove the back cover of your TV to see the internal parts inside.
Secondly,after you open the back cover and the internal parts will reveal.Try to find where is the power supply board.It is usually connected to the power cord and it have a AC input that connects directly in you outlet.
It look like this:
This image is not exactly looks like your power supply because you don't indicate the brand name and model # of your TV.
Thirdly,plug-in the power cord then power it ON and be careful,check the output voltage of the power supply using a multimeter (range in DC) ,if it is have a 24vdc for the supply of inverter board.
It is the board that gives a high voltage to the back-light of LCD TV.
Fourthly,if the power supply got the reading of 24vdc it means the power supply is good.Then try to check the input voltage of the inverter
if it is have 24vdc.
The inverter looks like this:
This image is not exactly looks like your inverter board because you don't indicate the brand name and model # of your TV.
Fifthly, if the inverter have a input voltage please check the output voltage of it.It should have 500vdc so be careful to perform the voltage data in that point because it has a high voltage or hot area.NOTE:
if you don't have voltage reading on the input of the inverter board (24vdc) and the power supply an output of 24vdc,please check the wire that connect to each other.
Sixthly, If the inverter board have a reading of 500vdc on all outputs connectors (it is usually have 4 to 6 outputs).Your back-light lamp at the bottom are busted replaced it.
Or if your inverter board doesn't have a output voltage replace it.
You can buy the parts here:
Just click this direct link. http://www.electronica-usa.com/Merchant2/merchant.mvc?Screen=SFNT&Store_Code=EU
And also to eBay.com at your search engine.
If you don't have any basic knowledge about the electronics and testing equipment please don't attempt to do this steps.Its better to send it to the qualified technician or on the authorized service center of your TV. I hope this solution will helpful.Thank you and good luck.