Are you 100% sure your battery is dead? The last time your battery was fully charged & worked, how long (hours & minutes) did the battery last?

If your battery was working fine & all of a sudden it didn't work...either the battery is bad, or the charging circuitry inside the computer is bad (assuming your charge/wall adapter is working properly as well).

If you think that your battery is still good...go to your local Apple store...and maybe they will check it for you.

Hope this helps,

- Nick