When it comes to computers/laptops, the most common cause for the absence of the sound is usually associated with the sound card driver. Even if there are all the drivers installed in the computer, the volume icon appears in the notification area and in Device and the sound card is recognized, it does not mean that the drivers are also installed correctly.
So, to troubleshoot audio issues, you should look online at technical forums, like IEC, to find answers to this problem. You can also try the following operations as well:
If you know the type of motherboard you have, download the sound driver for your model from the official site of the manufacturer. Or, if you have the CD with the drivers for your motherboard, you will find there your sound driver.
If you do not know the type of motherboard you have, and you are not skilled enough in computers to find out either, you can use a driver-pack, which is a set of drivers with automatic installation. This method is useful especially for desktops.
If the problem is not the audio driver, make sure the speakers and headphones are properly connected to the sound card, because you may have the surprise to find out that your pet has their own opinion about correct connections… Also, left-click on the speaker icon and make sure it is not set on Mute, then right-click on the same icon and select “Recording devices”. See which device is used for playback. Maybe it is the HDMI output and not the speaker output, because you connected the TV or something else to your computer.