I am attempting to connect my PC to my new Vizio TV.  The computer end is VGA and the Vizio end is HDMI.  I've bought an adaptor that is VGA on the computer end and HDMI on the TV end.  What am I doing wrong?  The PC is an old Dell Dimension Desk Top from 2006.

What are you doing wrong?  Coming here for help instead of calling the geek squad.

I ain’t your tech support old man.  Perhaps ask one of your grandchildren for assistance.

VGA is an old analog standard, and HDMI is a digital standard.  The adapter you bought may not translate the old VGA signal into a fully compliant HDMI signal, especially if the VGA feed is not 1920 x 1080 at 60hz (which is what an HDMI input is expecting).

A 2006 PC is ancient junk, that's at best a Pentium 4 based clunker.

Goob Squad? Those fucking idiots maim more systems than an Iranian prison.  I've made thousands of dollars over the years fixing the colossal fuck ups they cause.

My old HP Folio works fine for video on my VIZIO through an adaptor, just no audio going to the AV

My 3 year old ASUS wouldn't do audio either.

VIZIO says to plug the cord direct into wall socket with no extension cords, etc.

If already plugged in the wall socket, unplug it for awhile. I usually do that once every couple weeks.

get chrome cast

Maybe turn off CEC in the tv menu...

This. Just get a refurbished HP290 from eBay, it will pay for itself in electricity savings in a few months.

Or just get a new video card with HDMI output

Cheaper than a new computer but easily less than $100 Just make sure you have a compatible card slot and drivers for our OS.

If his computer really is 14 years old it will have none of those things.

Check the documentation on your adapter to make sure that it is designed to convert a VGA input from the computer to an HDMI output, rather than the other way around.  VGA to HDMI and HDMI to VGA are two different things (though visually you probably can't tell them apart), and they don't necessarily show the right one when doing internet searches, so you might have ended up with the wrong one if you did a google search and simply bought from a link that popped up.  You also won't get audio to your tv unless the adapter includes a connection to the computer's audio output, since VGA doesn't carry audio.

Also, check to see what type of expansion slots you have available for your computer.  Your current video card is likely a PCIe card, since that standard came out in 2002.  You could replace your card with a newer one with an hdmi output, though you'd want to make sure that drivers are available for your operating system, since it likely hasn't been updated to the current versions being used today.  The good news is that you wouldn't need a current generation card, and can get older ones for probably $80 or less that should work with your system.  If you don't have PCIe, then you will have a harder time finding a card with HDMI, or possibly finding a card at all.

Mike