it simple-ask him
The main places you need to look are in your computers basic internet settings since they can be easily blocked there. Another place to look is as madasalizard said in the background processes in task manager. (The easiest way to open it is to press Ctrl+Shift+Esc) And finally the last places you should look is in your router settings. If none of those places are blocking it, call your service provider about it to see if he had them block it. I know of only one or two service providers that don't block sites on request.
Neither can I...hmm, what does your brother look like and where can I find him?
have you checked in the background Processes by going in to task manager?