Problem with Acer Aspire 4920 notebook

Question

Dear Sir,
i purchaced acer laptop Aspire 4920 Notebook with windows Vista Home Premium preeloaded, 8 months back. Some how the windows crashed and i have no driver cd and windows cd with me nor i was given any cd. kindly help me to get the drivers and windows backup i have a sticker pasted at the bottom of the laptop with no key but a serial number which i can provide if necessary. i shall be grateful to you if you can help me in this matter.
Regards,
Adarsh
Chandigarh
contact : 09814213360
mail addrsess: >[e-mail]<