I really don't know if there is an actual solution.
I have now read a lot of posts on this and different people have had different levels of success with this. I am now using an optical cable which is definitely better than using the headphone jack but if you are stuck in headphone mode, I'm not sure switching to optical is going to solution the problem.
Due to the large number of posts on this, I think that TCL definitely has an issue with it.
It would appear that some people have succeeded in fixing it by hitting the jack, wiggling it around, one person stick a pen in it and cleared it that way. Another switched to using his phone as the remote then switched it back and it cured the problem.
Sorry I don't have a better answer.
I tried everything suggested on this website:
Thanks for your posting, but this sequence did not work for me. Still stuck in headphone mode.
Bummer! U did just like I listed? I was sure it would fix it for everyone since it seemed to logically address the malfunction that appeared to be going on, (i.e. a TV sensing a headphone that was no longer inserted.)
One shot of aerosol duster into the headphone jack on the remote instantly did the trick for me...
I had the same problem for about a day now. Try plugging your 3.5mm Jack into the yellow “Adapter” slot right above the headphones slot. While the Jack is plugged into the Adapter slot changer your TVs volume then unplug. That worked for me!
I couldn't find a pen that I could disassemble, like your fix, but I did find an eyeglass repair kit that just happened to be on my desk (I use this two of the same model tvs as monitors for gaming and my computer) and used the screwdriver that came with it. I slid the screwdriver in as far as I could and wiggled it back and forth and the sound came back.
Glad you got yours sorted out! Happy viewing.
I just tapped the outside of the jack lightly a couple times with my cell phone case (with cell phone in it) and it worked ok.