Ok easy ah! Will try to help ah!
Sorry Rolly, lame attempt to lighten up things.
Have you loaded or downloaded anything?
Sometimes computers have bad days; do you have a utility program?
I recommend Islo's System Mechanic to fix any computer glitch problem.
Download islo's system mech trial and go to Maintain, click PC Maintenance wizard and click next.
Easy. Restart computer and let it work.
I love this program.
Could be you need to download new drivers for your sound device.
If you have a sound card or on board sound, you may need to upgrade.
Let us know,
Your Hardware Guide.