To find solutions to a number of common problems with the Toshiba Satellite 2435-S255 look at the troubleshooting page
The Toshiba Satellite 2435-S255 is, by today’s standards, a large laptop. It has a blue & grey case (colors may vary). It is a member of Toshiba’s long running Satellite family of laptops, one which is still going strong today. It features an Intel Pentium 4 processor, NVIDIA GeForce 420 Go graphics card, a 15 inch display, and it runs Microsoft Windows XP. It comes with neither an optical drive nor a floppy disk drive, though it has an expansion port on which can be mounted a drive for either.
To identify your laptop as the Toshiba Satellite 2435-S255 look at the bottom of the laptop. If this is your laptop, then there should be a label or sticker on the bottom that says that the laptop is the Toshiba Satellite 2435-S255. See the image below for a picture of the bottom of the laptop.
Specs and Diagrams from Toshiba