Hello maria-la. I understand you're having some trouble with your sound.
Since the issue began today I suggest you first try using a System Restore to roll your computer back to an earlier time. This article explains how to perform the restore.
If that doesn't work I'd suggest you next try to remove the audio driver and allow Windows to reinstall it. Here are the steps.
- 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."
- When complete you should reboot your computer.
- Allow Windows to reinstall the driver.
- Verify whether the problem persists and post the result.
Have a great day!