Just bought an element 55" eleft556 tv and out of the box there is a white line on the top of the screen and is on all inputs so it's the tv and can't get it off. Need help

If you wish to get some details; check the site linked here. Pull up older posts.
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. Faults to all LCD & Plasma screen are similar, irrespective of its brand and screen size.

t-con board?

My first thought would be to check your TV on multiple inputs to verify that it IS the TV and NOT isolated to your input cable(s). If you can get a solid blue color to come up on the screen by changing inputs then it would really narrow down the issue(s).
Hope this helps.

You need a cable to go between the yellow (picture), red and white (sound) sockets on the strong to the VCR.

Those cables will connect to one of the VCRs AV inputs. You then need to use the VCR remote control to switch from the now defunct analogue tuner to the Line or AV input. Put your TV on the channel you use to watch video tapes. Switch on the Strong receiver. Do the switch to the Line or AV input on the VCR. When your VCR is on the correct input then you will see the picture from the Strong receiver on the TV. You can confirm it is the correct source by displaying the Strong's EPG.

When you come to make recordings, the Strong will need to be left on the channel that you want to tape. If your TV already has an aerial feed and isn't relying on the strong for its signal then you can watch another channel on TV.

Most set top boxes with HDMI also have a yellow video out and white audio out for connection to a VCR or DVD recorder. Connect these two RCA cables to the VCR's yellow and white INPUTS for recording. Set the VCR to LINE input. For VCR playback, connect yellow video and white audio OUTS from VCR to your TV's yellow and white INPUTS. Select this input on the TV set.

Same thing happened to me but it was my cox hdtv/dvr box, I exchanged it and it resolved the problem.

You have a problem in the vertical output circuit. Check for bad capacitors around the vertical output IC. The value of these caps are marked on the side of them. Thanks for using fixya. Please take a moment and rate this responce.

Do you happen to have a cable box? (reset cable box also by unpluging it). is that line also showing on dvd player on different input?

ok first connect the red/white/yellow output of the dvd to the top box red/white/yellow input. Get the extra a/v cable then connect to the red/white/yellow output of the top box to red/white/yellow of the tv a/v video input A/V1 or A/V2 and last connect the RF aerial to the top box antenna in.

This may not be the problem but its worth a try:
The plasma display screen is made of a matrix of elements connected to cables along the side and top. On your unit, some of these many, tiny connections are making contact intermittantly thus losing the elements in that area. These contacts are held in place with just pressure and if that is disturbed, you lose that line of elements. Try squeezing the cabinet of the TV on the outside at the top in the area of the loss and see if that makes a difference. May have to go inside and see if the contact assembly is disturbed or warped or something.