Dell 1505 laptop wont turn on help?

Something is wrong with mu dell 1505 laptop. I usually always leave it on but the other day it was off. When I turned it on I got the black screen that comes up when you don't shut down properly. I chose the option to start windows normally but computer shut right down and now wont turn back on. When I try to turn it on a few lights light up like the battery light and the capslock light. But the number lock and other light next yo it just blink for about 20 seconds or so then everything shuts back off. I have the plug lugged in. Why wont it come on? Could it be that the battery died and that it wont recharge or something like the power cord is bad? Help please thanks