How to reset tv. Have sound but black screen

Have you tried the T-con board?

Thank you,

Please check for bad electrolytic capacitors on both main board & power supply, if there is any "pup-up" one, replace it (them).

Blck with sound would be bad inverter or backlight

Blue withoutsound again inverter on the decoder is bad this does power both backlight and decoder so I would say inverter but check it into a shop as I cannot see the TV from here @ @ But I am sure my advice will give you a level playing field with the repair shop.

Thanks and please do rate postivly have a happy new year!

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/edwy_1a56970cf1ea4620

Look at the remote control: (page 14 of the user manual)
CC/Stop – This button will select the Closed Caption mode. The
options are OFF, CC1, CC2, CC3, CC4, TEXT1, TEXT2, TEXT3 OR
TEXT4. Additionally, this button stops the CD, DVD or VCR when the
component is activated with the remote control.

Download user manual here:
http://tv.manualsonline.com/manuals/mfg/vizio/gv42l.html
Please post back what you find.

It maybe a video board or LCD screen control problem. Best to use the warranty at this point. You shouldn't have to pay a dime for the TV breaking down this early.
Here's a link to help you get started on your warranty:
http://www.vizio.com/support/

The TV usually hums when the backlight setting is too low. So turning it up should get rid of the problem. To do this please follow these instructions:

1. Turn the TV on.
2. Press the Menu button on the remote, located right below the channel changing button.
3. Press the down direction button, located at the middle of the remote. Press that button until the backlight is highlighted.
4. Press the right direction button until the backlight is at 100.
5. Press the OK button and then the Exit button until you get back to your picture.

May be a bad power supply, which is a common problem with these units.I have a GV42L 42" manufactured in march 2007. It works perfect except the screen has a fracture on it. The warranty is voided because we damaged the screen. I can sell this to somone who has a good screen but needs boards or speakers, etc. Or I will buy your tv that has a good screen but damaged boards in it.
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I had this same problem. Vizio sent someone out to replace the motherboard. It didn't fix the problem. Since it was under warranty, they replaced it with a newer model VU42L. Doesn't have this problem, but it has others.

On the front bottom of the TV there is a little round eye. If that eye gets blocked, it'll reduce the range of the remote. Make sure there's nothing in front of it. Other than that, the sensor behind the eye could be bad.

Hope that helps...

Geno

If you are using a set top box this might be caused by turnig the box on at the same tie as you turn the tv on or slightly after you turn the tv on.  If you are using compnent or HDMI inputs the set needs to see the signal as it is turned on to know what formt the signal is in. 

I’m happy to help further over the phone at https://www.6ya.com/expert/dewayne_4a10eab6caecdb92