Led's power adapter jack is not working.

@maliktaqqi that could be caused by a bad barrel connector on the monitors main board. You would need to disassemble your monitor. Since iFixit does not yet have any guides for that, get the disassembly guide for the HP Pavilion 22xw. It should work for this monitor as well. you will find it on this page HP Pavilion 22cwa 21.5-Inch Full HD 1080p IPS LED Monitor, Tilt, VGA and HDMI (T4Q59AA) under the Document heading.

Once you have your monitor opened and have access to the main board, check the barrel connector to make sure that is is still properly solder to the board, If so consider replacing it by trying to find a replacement connector at places like Mouser.com or digikey.com as well as many others. If you can't find the connector, you can always check places like eBay etc. for a replacement board.

While you work on your monitor, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!