You can download HWMonitor for free. it will give you a rough idea of the wear factor on the battery. If it's like 12% or less then probably it's not your battery.
I have Toshibas. Here are some things that cure that on Toshibas:
While the PC is plugged in to AC, remove the battery, leave it out maybe 30 seconds, and then reinstall it. That allegedly tells the PC to expect a different battery and thus it actually analyzes the charge level.
and then do the things listed in this article, as well, and you should have reset whatever can be reset:
Battery not charging, not being recognized, or los... - Toshiba Forums
If none of that works, run it in to Staples or Office Depot or someplace that sells universal chargers and see if one of their chargers will charge it. If that works, buy that charger, lol. The battery in my Toshiba was over 3 years old and still charged, but the battery charger itself died.
eta: I have gotten that Win7 "uneedabattery" warning on a brand new Toshaba brandname battery that was actually 95% charged and had only a 2% wear factor. So I know that Windows can be wrong. I think I did the "Remove the Microsoft ACPI Compliant Control Method Battery" procedure from that Toshiba article and Windows quit giving false warnings.