macbook having problems to connect to the internet with cable

hello.

i bought a new macbook, at first it worked fine. i set up the internet, plugged in the cable and it worked fine until today when the internet just simply stopped working on my macbook. i plugged the cable back on my PC and it worked fine on it, but when i plugged the cable back to my macbook it shows that it is connected to the internet but i can't accesses any website whatsoever, i get the message that i'm not connected to the internet.
what should i do??? i have checked many times the internet setting, ip etc. and they are all correct, so what happened??

do you only have a high-speed modem? no router? no wireless router?

knowing your setup will help us answer your question.

in the meantime, try power cycling your modem with nothing attached to it or with anything attached to it powered off. then repower/reattach other devices.

as far as i know i have only one wire, no routers whatsoever!:/
i live in an apartment building, so the guy from ISP company just installed the wire in my apartment from the the building. if there are any routers or modems, than i can't access them.