is it possible to find my lost phone using the serial number?

I lost my iPhone last july 3 at about 12 pm. Then later that day, some guy texted my friend that he has my phone and he wants to take it back. I don't think that he has the intention to take it back because the number he use was cannot be reach and out of coverage area. Please help me to find it. I really need it because some of notes in school are there.