connect 12V-AC adaptor to headphone jack and then I've very low sound

[MohsenJim]

Hello. I connected a 12-V AC power cord to the headphone cord while the headphones were playing. It made a doping sound and the sound output power was very low and still the sound is very low even with the external amplifier. Of course, the computer speaker is healthy. What do you think happened?

[Prométhée]

Hello
well you're in luck if the computer isn't more damaged than that ..
An audio output is not at all able to support an electrical current input!
one or more elements may have been toasted

I already thought, that it was not a good idea, to make adapters with the same plug as a headphone output
I now have the proof!

[MohsenJim]

I quite agree. I made a mistake.

I did not know there was a device called an amplifier. I thought I could actiَvate the subwoofer by doing this. Now, when I play music, I hear the headphones with very little sound, and even the right and left, which I test, are absolutely correct. Can you think of a solution to restore the power of sound?

Maybe the electric charge has accumulated in it and it needs to be discharged in a special way? Because there is sound. Changing left and right also works well. So, as you say, one second of the AC power connection is probably not seriously damaged.

[Prométhée]

No, seriously, it is not possible to confirm anything to you, but it most certainly damaged something, something
It is necessary to consult a specialist, it is necessary to check, if there is not something to grill, and perhaps it is imperceptible

What idea did you have, it's a shame ..

although i highly doubt the result, try reinstalling the audio driver

https://support.hp.com/in-en/product/hp-all-in-one-pc-24-dp0000wi/32516390/model/38322327?sku=1V6B8A...

[itsmyname]

@MohsenJim -- I hear the headphones with very little sound

If you connect the headphones to your mobile phone, is the sound-level still very low, even when the phone is set to maximum sound-output level? If so, it could be your headphones that are "toast".

Got another set of headphones that you can try?

When you insert the jack from your headphones into the socket on your computer, there is mechanical (not electronic) movement.  

See the red-coloured "up-arrows" and "down-arrows". If the power-surge "burnt" those connection-points, you might not be getting a solid connection, and thus will get only a weak sound-level.

[MohsenJim]

@Itsmyname Thanks for your attention! 

If that's the case, it sounds good
What method do you suggest to solve this problem?

Because the sound is set to the highest level and I have tested it with different headphones, but the sound is still weak. I even tested it with a 45 watt external amplifier, the sound is still weak. So it is possible that the mechanical connections of the socket are burned

How do I fix the socket?

[Prométhée]

Sorry, @MohsenJim 
I told you there is hardly anything to do
a computer, is not designed to receive an electric shock through the headphones / audio sockets
As mentioned, I did not believe it so much, if updating the audio driver does not give anything better, your problem is most certainly hardware, the computer certainly needs to be fixed.
You are wasting your time here, I think, unfortunately, we certainly cannot fix this

[itsmyname]

@MohsenJim -- How do I fix the socket?

Unless you are quite familiar with disassembling a computer, to expose the headset hardware, and have the skills to unsolder the damaged hardware, and solder in a replacement, assuming that this is the cause of your issue, you should not make any attempt to fix it.  

Instead, find a highly-qualified "board-level-repair" electronics specialist, and pay them to inspect it, to see if something is "burnt", and then to repair the hardware.  But, it may be something other than "something is burnt" failure.  In that case, replacing the motherboard (or the whole computer) may be the only remedy.