Symptoms:
Have you looked at the help on the HP website? I answered a question very similar to this and found the answer on HP's website. If you have the specific model number of the laptop I would be willing to take a look for you.
Also, is there anything notable that happened when this problem first occurred? i.e noises, sparks, any visable damage?
Did the laptop work with just the power cord and no battery before? It could be that the battery is dead and the laptop will not power up without a battery attached, even with power connected.
Ok, after looking on the HP site, I found a few things.
Firstly, it looks like they have issued a recall on the batteries for your notebook. It says that this problem should not effect the working of the notebook though, which is fair enough.
If my battery pack has been identified as eligible for replacement, and I have had no issues with it, could the battery pack have caused any damage to my notebook?
No. The issue identified is with the battery pack only and not with the notebook.
Follow the steps on this page (titled 'Getting Started') to find out if your specific battery is part of the recall. If you battery is part of the recall then you can get it replaced. While this may not be what is wrong with your laptop, it is worth doing to be sure (and hey, you get a new battery for free!).
Secondly, there is a long page helping you to troubleshoot problems with a non-booting PC. This link will take you halfway down the document to where it starts to troubleshoot problems with power. Follow the instructions from there and see if that helps you at all. Post back with any successes/failures.
This is a hardware problem which can have many reasons.
It should be examined by someone with tools and spare parts, to try and trace it thru.
If the laptop is still under warranty, use it.
Otherwise, consult a repairman.
Plugged in, not charging
If your laptop refuses to charge the battery even though it acknowledges that it's plugged in, here's what you need to do:
Open the Device Manager by searching for it or right-clicking the Start button and selecting Device Manager.
Click Batteries on the list to expand it and you should see two items: Microsoft AC Adapter and Microsoft ACPI-Compliant Control Method Battery.
Right-click on each item and choose Uninstall device. Yes, you are uninstalling your laptop's battery drivers, but don't worry because they will automatically be reinstalled when you restart your laptop. Shut down your laptop.
Unplug the power cable from your laptop. If your laptop has a removable battery, remove it. My Lenovo laptop does not have a removable battery. I tried skipping this step but it didn't work, so I removed the bottom panel of my laptop and then removed the battery by disconnecting it from the motherboard.
Put the battery back in if you removed it. Plug in your laptop. Power on your laptop. Click the battery icon in the system tray and you should see that your laptop is plugged in and charging.
By reinstalling my Lenovo laptop's battery drivers and disconnecting its battery and then reconnecting it, I got my laptop's battery back to charging when it's plugged in. With differences in manufacturers, your mileage may vary. If you encountered this plugged-in-not-charging problem and found a fix that differs from mine.
