Why I can not open youtube apps in my iPad air? Anyone can help?

first thing happened was I can not open the youtube apps here in my iPad air. Then I try to delete it then install again but same thing happens. Then I try to refresh my iPad but still same thing happen again I can't open. Then I figure it out that maybe I need to update my software device from ISO 7 to ios 8 but worst thing happened. I can't open the YouTube apps again and my movie box apps I can't open also. And my iCloud settings i can't access also beacause they said need to check my email and verify my iCloud settings. But worst thing happen is I forgot my password in my email.. god! Can anyone help me pls of what I'm going to do? To fix this problem? Thank you!