No need to purchase anything, t1lavih.
Here you go,http://www.tim.id.au/blog/tims-laptop-service-manuals/#toc-toshiba
I would like you to go down to the line that begins with Qosmio, and click on X500.
The Toshiba Qosmio X505-Q850 is part of the Qosmio X500 series of Notebook PC's.
This is a PDF file.
You may have to allow up to 30 seconds to see the first page, and additional time for the file to fully download.
You will be only viewing it. If you wish to save it to your computer, and do not know how, please state so in a Comment, and I'll be happy to lead you through it.
This way you can then burn it off to CD disk for safekeeping, and delete it from your computer to save harddrive space.
I would also like to include this,http://www.irisvista.com/tech/laptops/Toshiba-Qosmio-X305/laptop-disassembly-1.htm
Not your laptop, but I thought the pictorial guide may help.
ALWAYS remember to follow Anti-Static Precautions.
If you have further questions please state in a Comment.