That specific model uses a standard ATX power supply. It should be straightforward to replace it with an off-the-shelf model.
Consider getting a Seasonic S12II 630 if you're on a budget. If you want a solid PSU that would work well in your next computer (in case the HP is totally bricked), consider getting a Corsair RM650x or an EVGA 650 watt GS, G2, or G3. For the EVGA models, get the one that's cheapest in your area. If they're all the same price, get the latest revision (G3 is the newest, etc).