Can connect to Firefox and nothign else

So here's what happened. A year ago, I updated YTD Downloader on my computer. It was working before I did this, and after I did, it said that it could not connect to the internet. Soon I realised that this had happened to all devises on my computer (includuing I.E.) except for my old version of Firefox. If I try and update it, it stops working too.

I've tried everything, including the obvious answers online. I'm not set to any 'LAN' settings, and I don't have any add-ons or whatever. Forums like this are frustrating because once other people get their answer, the chat is over, while nothing works for me. It's been a year, and it is truly VERY frustrating to deal with this for so long. Can't use aps, can't download a LOT of software, and can't get my audiobooks. Can someone please help me out? Hello,