I have a 98 S70, and recently replaced a failed headlight. However, even though all of the headlights are working fine, the light on the dash indicating that a bulb has failed will not go away. I have tried disconnecting the battery for a while but the light is still on.

Does anyone know how to reset the bad bulb alert light?

 

Maybe the light is telling you that you have another light out. Take a pic and post it. You may have switched on your REAR FOG lights and that is what you are seeing.
https://www.customers.volvocars.com/...98sv70_019.htm

Which light is lit?