Sudden no signal on digital channels on a Vizio VX37L

You have to go to your menu screen and change the settings from antenna to cable that should take care of it, and should be able to do a auto scan to load channel memory

This may work for you. My Vizio went black except for the blue channel rectangle in upper right corner; I couldn't change the channels or power off. I called Vizio, was told I needed a hard reset, and this fixed my problem: I unplugged the TV; held down the on button for one minute, then plugged it back in. It works fine now.

HERE'S THE FIX: I just went through this with my Vizio VX37L. TV is stuck in RGB input. This is the fix.... TV is stuck in RGB input.
(option 1) Power on TV, and press the INPUT button repeatedly and rapidly until you can change to a different input, such as AV.
If that doesn't work, try:
(option 2) With the TV off, press and hold the INPUT button on the side of the TV for about 5 seconds. The TV should power on and the input list will appear. The TV will no longer be locked, and the INPUT button should function properly after that.

Option 2 worked for me!

Same thing with my vizio vx37l tv. Did you fix the problem bpakja? If so please let me know how.

Tested and verified solution:

1. Set Tuner Mode to "antenna".
2. Run a channel scan. Should get zero channels found.
3. Set Tuner Mode to "cable".
4. Run another channel scan.
5. Celebrate!

I had the same problem. Check out my solution by viewing the subject titled Vizio 37L suddenly stopped getting all digital... Hope it helps!

Your cable signals are probably encoded so that you have to use their cable box for reception. Renders your tv tuner useless used for OTA.

I had the same problem with my 42" vizio. Was working fine for about a year and a half, then a month after all stations went digital, I couldn't see any digital channels and it wouldn't scan for digital signals
This is a strange go around, but it worked for me. . Tried unplugging, pushing power button for two minutes... did everything the forums suggest, with no resolve. But, here's what DID work for me. Trust me, it sounds strange, but it continues to work (and, yes... it's not a permanent fix... the channels still go out once in a while, but I can always get them back now)
Use your Vizio remote control. Turn your TV on. Press the "input" button until you get to "RGB", which is what you would connect a computer to. Make sure no computer is connected, or it's at least off if it is connected. When you get to RGB, you'll see a message that says "No Signal". After about 5 seconds, the TV will enter a sleep mode and seem as if it has turned off (orange Vizio logo). Once it completes it's little sleep cycle and "clicks" off, wait a few seconds and hit the input button again. It'll go to the next menu item. Keep clicking input until you're back on "TV", and VUALA! The channels are back! 
I accidentally figured this out when trying to troubleshoot, but I'm glad I did. Didn't want to dishout $250 to get it fixed. Let us know if it works for you too!

add each chanel manually

Did you hear any pops before the screen went black?
You've tried completely discharging it? Disconnect everything off the TV, all cables and power.
Press and hold the power button on the TV for at least 20 seconds.
Let it sit, and in about an hour, plug just the power in (directly to the wall) and see if it comes on. There should be an indicator light, is it white or orange now? Was it a different color before?
Odds are it's a board, be it the main or a video, don't know for sure. If you can take the back of the TV off and see if there are any evident signs of damage, blown or swollen capacitors, burnt traces or resistors/diodes, etc.