Sonds to me like a screen centering problem - First thing I would do, if you have kids, is assume one of them messed with a control - find your horizontal centering control and see if that will adjust it back right. If not, see if picture splitting was turned on - the option that allows you to show two different channels split on the screen, except in your case it may be showing the same channel on both sides.
If that does not work, then try a total reboot - see your owners manual for how to totally reboot the operating system - usually involves a power-up while holding in some button on the TV, or certain buttons onthe remote. I think what is happening is it lost its registration point on the screen, so what you are seeing is a half off-centered image, then the black edge, then the other half of the image "wrapped around" the TV from the other side. The other possibility is a logic board defect. Try the reboot - that might solve the problem. Unfortunately, you will have to reset any personal color preferences, channel skipping, etc you had programmed into it.
If that does not work I would google for the problem, with your make and model number and probably the phrase "split image" or "divided image" and see if there are any easy fixes on the web.
if that does not work:
General consensus in the past (see question below yours on same page) is that it is commonly cheaper to replace than fix, particularly when you consider the $200+ shipping cost to return it to the factory for a flat-rate replacement or about $70 for a TV repair shop to lookk at it and tell you the screen unit needs replacing for $200-300 - when a new TV costs about $200-300 in the first place, depending on brand. You could call a local TV repair shop and ask them if it is worth fixing.
You might google your particular make and model number with the word complaints added on to the search phrase, and see if there is a recall or replacement program or class action suit. There have been a number of manufacturers doing a flat-rate wholesale cost replacement for LED/LCD TV issues to avoid having a class action suit or recall, so you might get one from them cheaper than new, or a customer satisfaction rebate or coupon to reduce the cost - try out your customer service complaint capabilities.