Inspiron 9100 battery problem

Hello im new to the boards and i have a 9100 inspiron for a while now, When i take out the ac plug it should run on the battery but it doesn't it shuts off. and when i press the power button to run on the battery it won't turn on. The battery is fully charged, Is there something that i disabled on it? i looked everywhere on the internet about it but it looks like im the only one with this problem, ( it figures) but the notebook works with the ac plugged. I think after i updated it thats when it started but really didn't notice it until my girl knocked out the ac plug and the pc went off. Any suggestions? it's more likly something got disabled but i don't know. all my drivers are updated and my bios is updated and my QS is updated aswell but nothing worked. Thanks for the help.