Sound playback problems are not uncommon. Their nature can be diverse: a damaged or not included service, an incorrect driver, a failed sound chip on the motherboard, a virus, an outgoing speaker or headphone contact (this should be seen right now). In this article, we will discuss what may be the reason that the system loses sound, that is, media files play normally, but after a while they stop doing this. All reasons are listed, from hardware to problems with codecs and drivers.
To make sure that the sound is not lost because the audio chip wants to “give God its soul”, try booting from any Linux Live CD with a full graphical interface, for example, the latest version of Ubuntu and make sure that the sound works. Use this distribution for several sessions to catch a hardware fading sound, if any. It is clear that if the sound also disappears in Linux, then you should replace the built-in sound card with an external one, the problem will be solved (do not forget to disable the built-in via BIOS). You must also make sure that the motherboard is not "streaming". Look for capacitors swollen on top of it.
Only after determining the programmatic nature of the problem can one get down to business. A common reason that sound is lost in Windows XP is malware. Therefore, download the antivirus with the latest databases, Dr Web Cure IT is perfect for this purpose, boot in safe mode with command line support and carefully check the system.
It is still strongly recommended to use Zaitsev Anti-Virus (AVZ), specially created to clean your PC from such tricky "evil spirits" (one of the manifestations of the ancient one is already Net-Worm.Win32.Kido). For Windows XP with the indicated symptoms, install the Windows XP-KB958644-x86-RUS update, after cleaning the PC from viruses and with the network disconnected. Also, through the "Services" section of the "Administration" icon, you should disable the "Server" and the working "Station". For the future, you should generally close the ports through which this virus enters. A good solution would be to use the Windows Worms Doors Cleaner (wwdc.exe), which completely covers ports 5000, 445, 135, 137,138,139 and prevents future system infections. Do not you believe, to your naivety, that all vulnerabilities on these services have already been found ?!
And in more modern systems than XP, it happens that the sound disappears. Windows 7 is no exception. Everything that is listed below should be taken at the "seven" to localize and eliminate the malfunction associated with the inability to play media files.
Remember when the problem first appeared. If this succeeds, then roll back to the restore point before that date. If for some reason there is none, then open the device manager (Win + Pause> the "Hardware" tab> the "Device Manager" button) and make sure that there are no question marks in front of the devices. If they do exist, uninstall them and restart Windows. Virtual devices must be found, and sound must be made.
If this does not help, then install the latest driver for your sound card. You can find out the version of the chip from the documentation for the motherboard. The most common codec is Realtek AC 97. Another common reason that the sound is lost is the “crashed” Windows Audio service. You can view it through the "Services" icon in the "Administration" panel. It may for some reason not start. You can see the reasons using the "View Events" item. Then you drive the error number into the search engine and get a description of the problem and measures to eliminate it on the Microsoft website. It should be noted that the most common error is 1068, which the system issues in the absence of the included “Food Service”.
Quite often, if the sound on the computer is lost only in the video, there is a problem with the codecs. To fix it, use one of the stable fdshow builds, and not the popular K-lite Codec Packs compiled by lay people.