What to do when your HP ProBook 4420s power adapter not working?
When your HP ProBook 4420s power adapter is not working, the first thing you should do is to verify that is the problem with your AC power adapter or the notebook computer. There is a quick test you can use. Plug the AC adapter into a different notebook PC and check if the computer works normally. If the notebook PC operates normally, there is not a problem with the lapop AC adapter Use a different AC adapter with the same notebook PC and check if the computer works properly. If the notebook PC operates properly, there is a problem with the original AC adapter. If the HP ProBook 4420s AC adapter is defective and the computer is in warranty, contact HP service and support for further assistance. If the computer is no longer in warranty, you can get a high quality replacement power adapter for your HP ProBook 4420s.