Learn Italian: Non conosco nessuno dei tuoi contatti. - I do not know any of your contacts.

The verb conoscere means to be familiar with a person, place, or thing. Since contatti (contacts) refers to people you are acquainted with, you must use conoscere. Sapere is used for knowing facts or knowing how to do something.

Why does the sentence use both non and nessuno? Isn't that a double negative?

Yes, and that is perfectly correct in Italian! When a negative word like nessuno (nobody or not any) comes after the verb, you must put non before the verb.

Does nessuno mean "nobody" or "any"?

It can mean both depending on the context. By itself, nessuno usually means "nobody" or "no one." But when followed by di (of), as in nessuno dei, it translates to "none of" or "not any of" a specific group.

Why is it dei tuoi contatti and not just di tuoi contatti?

In Italian, possessive adjectives like tuoi (your) almost always need a definite article before them. Here, the article is i (the plural for masculine nouns like contatti). When the preposition di (of) meets the article i, they merge into the combined word dei.