Sometimes it happens that as a result of reinstalling Windows, or performing another similar operation, the sound disappears. This problem can be solved very easily.
The fact is that to play sound, Windows uses a so-called "Sound Card", which can reproduce sounds. However, for this device to work, Windows requires special software (a driver).
Such software, which allows the use of various devices, such as a modem, USB port, etc., is called a "Driver". In professional circles, they simply say "Drivers".
It is thanks to drivers that Windows successfully accesses devices, gives them commands, queries them, and performs many other operations. If sound has disappeared in Windows 7, the problem is most likely that this very "Driver" for the sound card is simply missing from your operating system.This problem is solved simply: you just need to find out the name of your sound card and install the appropriate driver. Often, special disks with the corresponding drivers are provided with the computer. You can also download drivers for the sound card from the internet - I wrote about how to do this in the article: Sound disappeared after installing Windows.
If you do not know the name of your sound card, we advise you to try downloading a driver called "High Definition Audio Driver", which will most likely work for you. Otherwise, you should either disassemble the computer and find out the name of the sound card, or get the device code in the Windows Device Manager and search for a driver by the device code on the appropriate websites on the Internet.
Or you can contact a professional who will fix the problem in the shortest possible time, and for a relatively small fee.
Good luck!