Thank you Bookworm for your reply. But none of the 2 problems mentioned is happening in my case.
Check these out
Go to Control Panel / Sound & Audio Devices / Audio tab / Sound Playback – click on down arrow and check that the correct audio is selected. Typically the problem will be something “modem line 0 playback” has been substituted for the correct audio device.
It has got Sigmatel Audio as the only option and that is selected.
Start / Control Panel / Administrative Tools / Component Services / a separate window will open – in left pane click Services(Local) / Scroll down to Windows Audio service / if the service is Disabled or Manual right click > select Properties > under Startup Type change to Automatic > click Apply > click Start > Reboot.
The service is automatic and is started.
So don't really know now what to do. Anything else I can try?
Thanks