Please do try these troubleshooting steps that may help in solving the issue.
- Start by uninstalling/reinstalling the sound driver.
- Go to Device Manager and uninstall the Sound Card driver.
- Next is to download and install the latest driver from Samsung's Support site.
- Here's the link: http/www.samsung.com/us/support/owners/product/NP300E5A-A01UB#
- Once installed reboot your laptop for the changes to take effect.
- After the reboot make sure that your Playback Device is set to your Speaker.
- Test it again after all these troubleshooting steps.
- If all this will not work I would suggest running System Restore and restore it to the time before the problem even happened.
- Lastly, your last option would be to reinstall Windows if System Restore will not work.