So my mum cleared the history and now where videos should be it's just black. I need to fix this quickly since I don't want to miss the livestream and there's a lot of Youtube videos that I want to watch. Does anyone no how I can fix this?

Sounds like a problem with flash. Try downloading it here: Adobe - Install a different version of Adobe Flash Player I hope this helps

No it's up to date but isn't working. I managed to watch the livestream but Youtube still isn't working.