PLEASEE HELP! I'M GOING INSANE! why won't the video application on my computer work?!?

so one week ago i was able to watch videos on websites such as youtube and the cw but just a couple days i wanted to watch an episode i had missed on the video cw but it wouldn't work!! i mean, the site uploads but then there's this white box where the video should be. the video itself doesn't appear and my dad doesn't even know what to do about it...! and he's pretty tech savvy. please help meeee!!!!