What's wrong with my battery?

I have a Casio Exilim camera and the last time I used it, the battery died. I just figured I'd charge it the next time I wanted to use it...which was today. I put it on the charger and the red light kept flashing; I didn't remember that it was not normal so I sadly ended up not bringing my camera with me tonight, cause it was still dead when I was leaving and I figured it'd be fine when I got home. The battery still isn't charged, it's not even warm! I looked in the reference book and it said when it's charging the light will be a steady red, and turn off when it's done. Like I said, it's blinking red.......what am I supposed to do? I don't know what's wrong with it! Help please =(