I have a white macbook. I went on holidays and when I returned,the battery had and x through it. It wasn't plugged in. I try and check the cycle count,but since it doesn't recognize the battery,it won't say. thanks
You may also want to update the battery to the newest version, 1.4. It can be downloaded here.
If that doesn't do anything, go to the Apple menu > About this Mac. In the window that opens, click "More Info". This will open System Profiler. Select "Power" from the menu on the left, and look at "Battery Information". Check where it says "Cycle Count".
If the number is under 300, and your battery isn't working, it may be eligible for replacement. If it's over 300, then it's probably time to buy a new one. Batteries are like tires on a car, eventually they'll totally run out and you'll have to get a new one. It's the same for all rechargeable batteries, for either a Mac or a PC.