Youtube won't work. Slow downloads.

Hello,

I am hoping someone can help me here. I have tried EVERYTHING. So up until a few weeks ago my computer was working perfectly. Then one day I went onto youtube and the videos weren't playing for me. Just a black screen. This is really weird considering I can watching videos everywhere else (except Facebook, Facebook videos give me issues too). So not only that but whenever I need to download something or update it either dowloads to a certain percentage and stops or doesn't do it at all.

Something is telling me it is my internet connection because If i switch over to a neighbors really weak connection I can watch videos on youtube. My internet connection has always worked perfectly and it shows it has all the bars right now. This problem literally appeared out of nowhere.

Can anyone help me?