Well it's either the AC adapter or the charge port.
If you have a multimeter, you can test the voltage output from the AC adapter while it's plugged in to make sure it's outputting the correct voltage.
While the AC adapter is plugged in the laptop, does it wiggle around? If so, it may be busted. Did a quick search, and looks like you can get a replacement for fairly cheap: http://www.amazon.com/Eathtek-Toshib.../dp/B005J2X6VY
Would require you to open up the laptop and swap out the power jack, though.