Computer wont turn on.

Is there anyway to check if the power supply has failed. How can I prevent this from happening again.

Is there anyway to check if the power supply has failed. How can I prevent this from happening again.

1.  Make sure that there's power from the wall outlet, if you haven't already.
2.  Although it's very unlikely that the power cord itself is at fault, you should try a different one if you can.
3.  If there's power at the outlet and the power cord is OK, and there are no lights or any other sign of power in the computer, it's likely that the power supply is dead.

I don't know how old the computer is, but PSUs will fail sooner or later, usually later.  I've never been inside of an AIO computer, but I suspect that replacing the PSU isn't as straightforward as it is with a regular desktop PC.   Also, if the PSU did fail suddenly, it's possible that it took the motherboard along for the ride.  This sort of thing can result from a lightening strike or other power surge, and if that's the case, the general preventive action is to use a good surge protector.  If the PSU failed due to old age, there really isn't much in the way of prevention that can be done.  Unless you're comfortable with poking around inside the case and can test the PSU output with a volt meter,  I would recommend professional assistance.

Try running the HP Hardware Diagnostics Test

http://www8.hp.com/us/en/campaigns/hpsupportassistant/pc-diags.html

Wayne