How to fix TV volume, internal problem?

If you have an old shelf stereo system you could run red/white audio cables from the tv's audio out into that system and if the problem is a tv speaker issue, sound will be fine from the stereo. Go into the tv's set up menu and select external speakers from the audio menu.

If it's something with an internal part, the cost of repair would be much more than the tv is worth. Check your local craigslist for a used tv to replace it.

If you have to ask, you're clearly not trained to do so.

Modern electronic products are not designed to be tinkered with by unknowledgeable people. It's dangerous - for both the appliance and you.

Either take the TV to the shop, or, based on the fact the TV is probably older than you are, buy a new one for Grandma.

Does the TV have audio-out plugs on the back? It might be easier to just set up cheap thrift-store stereo than try to fix the internals of a modern TV. You'd lose the volume control that way, of course.

I have a $35 (used) surround sound unit on my TV that came with its own remote. The remote that came with our cable box can either be switched to talk to the surround sound unit or can control the audio level that's output from the cable box itself.