My Laptop suddenly turns off sound

When I play game or listen to music, It suddenly turns off sound. If I hit the mute button and hit again, It will OK. Or, I change the volume, It works.But after time, It turns off.Is this hardware or software problem. I remember that everything is OK before I bring my laptop to Clean Center. What should I do? I'm using Windows 8.1, my laptop is ThinkPad T410.
Thank you!

This should be related with the sound driver. Like Tripler suggested, update your sound driver would fix this issue.
For sound issues, you can refer to the following article if any further issues:
No sound in Windows - Windows Help

Regards