Toshiba serial number sticker removed

First off start using the program: Mainboard DMI information viewer (current ver 1.0). If the string is gone here – then u need to take pictures of the HDD/ODD/BAT (with each of the serial numbers visible) and contact the manufacturer. These serialnumbers in combination only matches/is unique to one unit serialnumber (the one you are after). Unfortunly, this type of work – and forwarding of information usually only happens between a service-partner and the respective manufacturer…

The serial number being removed is sometimes a sign that a product is what manufacturers call "Re-Manufactured" -- in layman's language the laptop has been returned by a customer and they've issued him with a new one and fixed his later and sold it off cheap. So if you bought the laptop as new, I'd have a word with the retailer.

In the past Toshiba marked such models clearly.