Is there audio from any other program or browser? If yes then please try Safe mode

If not contact your computer maker.

You might need to install some audio codecs. I was using K-Lite codecs with Windows XP.

See:

• https://support.mozilla.com/kb/No+sound+in+Firefox
• https://support.mozilla.com/kb/Video+or+audio+does+not+play

You can click the Volume icon on the Windows Taskbar near the clock and click the Mixer link at the bottom to open the mixer.
You can adjust the volume level for each application in that window, so make sure that Firefox is not muted or set at a low level.
You will only see the Firefox program in the Mixer if you are on a website that plays sound.
Also check the volume setting for the plugin-container process.

Managing the Flash plugin

• https://support.mozilla.com/en-US/kb/Managing%20the%20Flash%20plugin

Also see this - Video Test Page

• https://support.mozilla.com/en-US/kb/video-test-page

Check and tell if its working.

Well guys I tried some of your suggestions but still not working. Safe Mode didn't work. K Lite Codecs didn't also.

Right now I disable all plug-ins and extensions. Didn't work either it seems.

Went to Device Manager/sound video and game controllers... everything is fine. Didn't show the yellow (?) mark.

Scan with Avast/Spybot S&D/Malwarebytes... nothing wrong or so it says.

@mha007 the video test page works (shows video) on the one with flash but still no sound.

@cor-el I can't seem to find the Volume icon near the clock in my Windows task bar. I've seen what you mean about the mixer but I just can't find it. Also I don't know how to check the volume setting for the plugin-container process...

I can't seem to find the Volume icon near the clock in my Windows task bar. I've seen what you mean about the mixer but I just can't find it. Also I don't know how to check the volume setting for the plugin-container process...

If you want the volume control in the system tray, you can set that in the Control Panel. You might want to re-install your sound drivers.

Windows XP doesn't have the mixer available from the volume icon on the Taskbar if I remember correctly, so you can ignore that part of my post. In Windows XP there is only one global volume setting via that icon and not for each application like Windows Vista and Windows 7 have. You can still check the setting in Control Panel > Sound if that volume icon is missing on the Taskbar.

@finitarry, I re-install the sound drivers twice and restart computer. Doesn't work either.

@cor-el, Yes I read that Windows XP doesn't have the mixer anymore but wasn't sure. I check in control panel > sounds, speech and audio devices. Check the system volume/accesibility sound option/advance volume control/speaker settings... everything looks as it is supposed to as far as I know.

Nothing was muted. Everything in proper place though I move some of them up to see if something changes. Nothing did. I can watch web site videos/DVD movies with VLC (DVD writer) but still no sound.

Did a system restore a couple of hours ago and didn't work. I don't know what else to do. Seems that the only thing is to restore Windows again. Wich I don't like.

Btw, I have FF 3.6.18... I don't think it matters since everything was working just fine but who knows...

If there is no sound at all from any application then make sure that the correct sound output device is selected in Control Panel > Sound.

You can also do a DirectX Diagnostic check with the MSINFO32.exe program.

• Tools: "DirectX Diagnostic"

Well finally is working!

After leaving the computer for a day without sound drivers and disabled plug-ins/extension I did yet again some of the above suggestions.

Install the drivers again and check every plug-in/extension... also verify volume controls and all that stuff. Check also activex with run > dxdiag... also with MSINFO32.exe

What I noticed though, and maybe it was the problem all along, is that the speaker's plug was a bit loose. Adjust it and everything is just fine. I hope it stays like this after all the stuff I did with the PC.

Thanks for your help guys. I appreciate it from each and everyone of you. Big upZ!