Please note that ANY Internet connectivity questions go in the Networking forum, so I'm moving this thread there.
And please, provide some detail. You've basically asked "why?" so we're all responding with "why what? We need to know EVERYTHING: your ISP and what type of broadband connection you have, your hardware, particularly the brand and model of modem and (if you have one) router. And you say "i tried," but you don't say what you tried-that would help a lot.
Oh, and WELCOME TO THE MACNN FORUMS!