Snabaraj,
Plan A: Contact Toshiba and inquire if recovery/reinstallation DVDs/CDs are available for your computer--if so, purchase and use.
Plan B: Find a friend with a systembuilder/OEM DVD for Vista Home Basic (VHB). Install VHB on your computer using that VHB DVD BUT use the Product Key on YOUR CoA label on the bottom of the laptop. DO NOT use his Product Key. DO NOT use a copied DVD or an iso of a downloaded DVD---almost guaranteed to be loaded with rootkits, viruses, and malware! Oh my!
When it comes time to activate, use telephonic activation.
For great advice on all topics XP, visit http://www.annoyances.org/exec/forum/winxp