how do I fix the power adapter not recognized problem

I see that a lot of folks have had this problem...I unplugged my laptop and operated off battery for a while and when it got low went to plug it in and the Inspiron E1505 does not recognize my adapter...I have an after market adapter because when it was a year old the other one died, along with my battery...funny how this happened JUST out of warranty. I see this a common problem. Anyone have any solutions? I am reading it could be mother board or is it??? mayday mayday