Are these the front panel USB ports or the back panel USB ports on the motherboard?
You can check the connector cables on the case front panel ports and see if the connection to the motherboard USB ports might have come loose, either on the case end or the motherboard end.
The HP Pavilion 9000 is a laptop. This advice does not apply. Dead USB ports on laptops can be a pain that usually can only be resolved by the manufacturer, unless you are a repair man or if it is software related.