D-Link DI-624 won't work!

Hi, I have D-Link DI-624 Router installed on my brother's computer. At the beginning, it worked normally, but now it stopped working. My brother can connect to the internet, but I can't. I called the broadband server because one of their maintanance guys had said the signal was incoming weak, but the new guy said that if my brother has internet, it's because the router has to be reconfigured. How can i do that??