I have sound but have a black screen with a horizontal line across it

https://www.youtube.com/watch?v=wt1TBOGRStoSome common symptoms of a problem that could be the y-buffer is that you have no picture on the screen, you have black lines going across the screen. Those lines are typically horizontal and they go all the way across the entire screen. These black lines could also be caused by damage to these ribbon cables.
https://www.youtube.com/watch?v=DZZqj3eW248

To clarify, are the 3 black lines horizontal (left to right across entire width of screen)? or are the 3 black lines vertical (top to bottom across entire height of screen)?

Horizontal lines are almost always the result of a failed panel, and no board replacement will fix the issue.

Vertical lines such as you have described (only 3) are probably also a bad panel. If the black lines were evenly spaced in a repeating pattern, it could be a mainboard or TCONN board.

Has this panel been cracked? or perhaps cleaned recently with too much water or cleaning solvent that has gotten the screen wet?

You may have to sell the TV for parts.

If you wish to get some details; visit the site linked here. Pull up older posts. Surf the site with patience. http://electronicshelponline.blogspot.com/
Line, faults & possible causes to LCD & Plasma screen are given with illustrations. You can get an idea about the fault to an extent.

hi i have the same tv mine just started doing this last week were you able to fix the problem if so wht was it

panel needs replacement, better go for a new tv

This could be a capacitor if your lucky but can also be the horizontal transistor. The repair could cost you between 60$ and 150$
My opinion; it's not worth it.

It looks like you've got problems with your screen. If that one is on a warranty, replace it

Hi,
I hope your TV model is Sony KV-G21M1 and you see color bars as horizontal lines across the screen.
Let me now are you tech guy or know how to repair TV to guide you further.

A line on an LCD, either horizontal or vertical usually means the video driver board is defective or the screen is defective, does it show up as black even on a dark screen? That means a line of LCD "shutter"s is not working and there is a problem that cant be fixed by a reboot or channel change. Bummer.

hi, sounds like the screen has a bad connection. Are the horiz lines the same shade all the way across?