Problem with my sound system on my computer....?

ok I have older emachines(2005 maybe?) AMDSempron processor3100+. It is saying I no longer have a sound device. Now my computer sound effects for my windows (ME) still work but nothing on my yahoo, youtube, pogo etc. when i go to control panel>sound and audio devices it says it has no audio device. I have gotten several errors when restarting and will list as they happen. If anyone can help walk me through this it would be greatly appreciated