If there's no installation or recovery disc, there must be a recovery partition you can boot into to go back to factory settings. Read the manual or ask the IT-staff of your school. Or she should be able to order recovery discs from Toshiba.
It's a common thing to do: go back to factory settings, and it's surely possible by one of the 2 methods above.
My friend came to me with her laptop (Toshiba portege) running Windows XP completely overrun by viruses. The computer will not connect to the internet. She has no antivirus software on it (I know, I know). We tried to install Microsoft Security Essentials on it after downloading the installer on another computer and transferring it but the installation would not complete. We booted it in Safe mode and tried to do a system restore but it said system restore was infected so we couldn't even do that. It seems like the only option is to totally wipe it clean, but the OS came preinstalled and she does not have any installation discs or recovery discs. What can we do? If it helps, I have the exact same computer (these are school issued laptops). Can I somehow use files from my computer to restore hers provided we have her license key? I have an external enclosure so I can take her hard drive out if I need to, but everything I have tried to look at seems to say if you have XP and no software discs you are out of luck.