Hello thaher. I understand one of your speakers is not working.
The most common cause of a single speaker not working is a hardware problem, such as the speaker being busted. However, a good step to take would be to remove the sound card's drivers and allow Windows to reinstall them. Try the following.
- Press the Windows+X key combination. This opens the Context Menu.
- Select Device Manager.
- Expand the "Sound, video, and game controllers" section.
- Right click on your sound card and select "Uninstall."
- Reboot your computer and allow Windows to reinstall the driver.
Have a great day!