TV won;t come on.

Here's the test. With the TV on shine a flashlight on the screen. If you can see a dim picture the backlight circuits are bad. If you cannot see a picture the T-Con board is bad. You can get parts from here: TV Parts Universal TV Stands DLP Chips ShopJimmy

There are lots of common problems with flat screens that result in those symptoms. Some fixes are super easy and cost $.35 haha and others can cost hundreds not to mention if your doing it your self or not factor in labor. Lots of people sell tv s like that from $50 to $100 bucks and they sell quick! Hell I'd buy it if I had the chance. Could use parts or god forbid find an easy solution ( rare :( )

Check and replace its main power regulator board as card basis.

I'm looking at the picture of the inputs/outputs for your TV, and it appears that your only audio-out option is digital (the "AUDIO OUT/COAXIAL" orange output). You won't be able to just plug speakers in directly. If you have a receiver/system with a COAX input, you're good to go. If you have analog equipment, the digital output won't work.

Replacing vertical output IC won't poise this type of problem. Check the voltages at the audio output section.

is there sound?

Sound like a mainboard failure

http://www.shopjimmy.com/dynex-cbpf7z4kq9-main-unit.htm

I say press the input button until you see a picture!.

may have some loose connection inside the tv occur, or a tv circuit problem already

You need state whether your tv is an LCD tv or a plasma tv????