Have lost Volume Control Icon & Sound on Windows 98

I hooked up a new monitor to my pc and all of a sudden all my sound is gone. also no volume icon on the task bar. Ran Norton and it fixed what problems it found (2) but still no sound. The volume button on the keyboard doesn’t work either. Can someone head me in the right direction or tell me what to do? Please email me here or at gpwn@msn.com (home pc).

Thanks so much!!
Waverly