OK, an update. I've done some thorough research on your particulat laptop and Toshiba definitely do NOT list instructions for performing a Refresh install (or 'In-place upgrade') of Windows XP. They list instructions for restoring the drive image to its original factory state, but that will destroy all data on the drive, including installed programs and data files.
See this article about it.
In fact, the only way to refresh your Windows installation might be to purchase a retail copy of Windows XP and do the refresh from the Windows CD.
That's a pretty drastic step to take of course, but so is the prospect of losing all your programs and data.
Before you go to that extent you might want to have a serious attempt at rescuing your laptop from the infestation(s) that is (are) causing your problems. Use your antivurus program to thoroughly scan your system from 'Safe Mode' and clean any virus infestation that it finds. Then follow the relevent procedures from the article
"Boot, dammit, boot!" to see if you can get it back to an operating state. That article's been put together for situations such as yours, and contains a lot of useful information.
Finally, contact Toshiba's support team to see if there's an easier way to do a Refresh install than by purchasing another copy of Windows XP.