If your problem is just around web pages, the first thing to do is check if it's just one page you can't see, or whether it's all pages.
If it's just one page, the problem is most likely down to the website you're trying to visit.
It's also worth checking that you're using the right URL.
But if you've done this and found that the problem affects more than one page across more than one site, then it sounds as if there's a problem with your equipment. It could be your router, modem, or computer.
The best way to find out and to try and fix the problem is to visit our Repair Centre. It's simple to use but effective: we'll take you through a series of steps, we'll run some tests on your line, and (if we can't fix the fault there and then), we'll arrange for an engineer to come out to you (where that's appropriate).