If you can, try taking off the panels on the bottom of the laptop and look for a small coin battery. See if it's one that's soldered onto the board, or if it's just a plug. Be sure to take the laptop battery out first.
If the coin battery can be seen and is a plug, just remove the plug for a minute or so and plug it back in, put the battery back in, and boot back up. If it's one that's soldered on, then you'll pry have to send it into Toshiba; I remember seeing this fairly often with some Toshiba's a few years ago. We had to send them all back to Toshiba and get them worked on. You can see if they will do it for free or not if the laptop is out of warranty.
Edit: Found this... Depending on the brand of BIOS you have, you could try this list: Toshiba L300D Bios Password - Page 2
Another article: http://www.cgsecurity.org/wiki/CmosPwd