is the user manual for your Dell.
On the same site I found this article - which discusses the ac adapter etc.; and it mentions both a green light on the power adapter, and a blue light on the connector to the laptop. The lack of a blue light suggests the adapter has failed, is not charging? If so then you need to test with another adapter?
And this is the first section:
Check the AC Adapter
Unplug the AC Adapter cable from the notebook computer.
Check for any physical damages to the AC Adapter or the adapter cables. Refer to Dell Knowledge base article AC Adapter Damage for more information.
Check the power indicator light on the AC Adapter.
(Look for a green light on the AC Adapter block or a blue light on the connector that attaches to the notebook computer.
Does the power adapter charge the battery or not; I suspect not?