where can i get a instruction book for my laptop????

First place to look for it : samsung.com
Look for Support or Download.
Next, you can search on manualslib.com, manualshelf.com, manualscat.com, all-guides.com, lastmanuals.com or manualzz.com
Those sites contains all sort of manuals, even those that the original maker no longer have available.

And, as N told you, enter the brand and model of your laptop into your favourite search engine and you'll surely find it.

Electro
December 2017

SAMSUNG NP350E7C USER MANUAL Pdf Download. - ManualsLib just type that into google and you will see your manual

n
December 2017