Westinghouse ld-4258 no picture but have sound

Fault at its main digital board. Short circuited component/s at it. Contact any service technician; or the authorized service center. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts.
http://electro-medical.blogspot.com/
http://electronicshelponline.blogspot.com/
In most cases, the main board might have to be replaced. If so, a software [firmware] update too might be necessary.

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Westinghouse 22" LED 1080p 60Hz HDTV ' LD2240

www.amazon.com/...1080p...LD2240/.../B007ATHRJ...

Amazon.com, Inc.
Rating: 2.9 - ‎21 reviews
Amazon.com: Westinghouse 22" LED 1080p 60Hz HDTV ' LD2240: Electronics. ...When I set it up I was disappointed with the sound but not surprised, it is a cheap TV... Apparently this is not an unusual problem for Westinghouse. ... Oh well, I tried. ...VideoSecu Articulating Arm TV LCD Monitor Wall Mount, Full Motion Tilt ...

Westinghouse 22" LED 1080p 60Hz HDTV ' LD2240

www.amazon.com/...1080p...LD2240/.../B007ATHRJ...

Amazon.com, Inc.Westinghouse 22" LED 1080p 60Hz HDTV ' LD2240 ... When I first hooked it up to my cable connection, through the coax connector (TV ... When using as a computer screenthere's an auto adjust and full manual control .... have endured compromised sound and picture, but I've never had this problem. .... Oh well, I tried.

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
Some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement.

Simply contact their support at the following link: http://westinghouse.com/contact-us/ but know what your model number is (not the serial number).

I think you are not allowing the scanner to actually find the channel before switching out of the menu. I can think of no other explanation for both manual and auto functions to fail (unless you have a lemon).

If you do not have a manual, you can try one of the alternatives below.

Or, you could try to google for the manual for your particular model of Westinghouse TV and find the procedure there. Below I simply list a couple of manuals that may be applicable but clearly are for two models of Westinghouse TVs.

Manuals Online offers a simple to understand procedure (if you can download the manual, I have trouble reading it in my browser for some reason). The information is on page 43 of this alternative. http://tv.manualsonline.com/manuals/mfg/westinghouse/ld265.html?p=43

It has diagrams of the menu.

Pages 35-38 of another manual covers both automatic inclusion and manual addition of channels on a particular Westinghouse TV. http://westinghouseelectronics.com/wp-content/uploads/2010/05/LD-4258-User-Manual.pdf

http://westinghousedigital.com/wordpress/wp-content/uploads/2010/05/LD-4258-User-Manual.pdf
Try this link to download the user manual. It has all details. Gopakumar Gopalan Google

If the set is still under warranty, the power supply board is going bad. If not you can replace it yourself. It's not that big of a job. You can find the parts you need at www.shopjimmy.com

lg tv model 21fj8rg3t8
H OUT (2) folister capasiter valu

If picture is OK, and the fault is with its sound only, the repair cost will be less and can be repaired. Check its speakers first before proceed.

Using the remote go to the menu for the TV. Look for picture or aspect ratio. Make sure it is set to 16:9 and not zoom or auto. That should clear the problem up.

http://www.fixya.com/support/t10640288-westinghouse_ld_3235_picture_goes_in_out
did you tried that?