Blue line across mid screen - Toshiba CN36Z71 36" TV

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

Sound like your Y-Sustain board has one foot in the grave. The Y upper buffer and Y lower buffer boards go when the Y Sus Goes too...

Go to a unused video input and examine the screen----if you see blue with slightly curved trace lines the blue screen control for the set is set just a bit too high.

Loss of vertical sweep or deflection.

The issue is that the monitor in not getting the signal. This tells me that the video adapter ( or on board video) has went bad. Try another video card if all your doing is social media and surfing you can pick one up for around 20.00

You haven't stated whether there is screen or picture. If you see only a blue line across the screen with high brightness, vertical output Ic of your TV has burned out. Don't switch on the set further or increase its brightness, till the fault is retified. Otherwise there will a phosphur burn occur where the blue line is now, and it is internal, whcih cannot be retified anymore.

Problem #1) Convergence

Symptoms:

• Screen Looks 3D
• Colors wont align
• Video may look distorted

Problem #2 CRT Fluid has clouded over. Symtoms

• Dull looking video
• White looking video
• Halos around objects
• Red/Orange looking video

You can see some examples and find a fix here...

http://www.fixya.com/support/r2861467-solution_video_looking_whiteish_dull

Adjust your convergence. Under menu I think its the last choice at the bottom of settings or picture menu

What is the model number of your set?

Those lines sound like "retrace lines" and several things can cause them. The most common are shorts inside the picture tube and shorted semiconductors in the video driver circuits. They can also be seen if the blue screen voltage is too high or if someone has tampered with the screen voltage control.