Toshiba's, to the best of my knowledge, don't have a recovery partition. They come with recovery discs and you absolutely need to use those discs to restore the computer.
Put the CD/DVD recovery disk in the drive and shut down your computer.
Start it again as soon as you see the red Toshiba logo, press F12.
(you may have to try several times, it is tricky to get it right)
You should then get a small 3 or 4 part menu, choose to boot from CD and follow the prompts.