The buzz doesn't tell me enough to hazard more than a "it's broken and needs repair" answer.
The usual TROUBLESHOOTING THE DEAD PC on google gets you started if you are new to troubleshooting. You find these articles follow the usual "Make it as small as possible" to see if it works with as few parts as you can manage.
Packard Bell desktop - when press the start up button just get continual high pitched buzz but nothing else happens - would normally be same noise for a few seconds then start up commences
Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic