Hi there 'Sheenaroulst',
The 'Youtube' application was removed from the IOS due to seperations of companys. The 'Youtube' app can be found in the app store on your iPad, just search 'Youtube'! (just making you aware)
Check your connections to your device, are you signing in using cellular or wifi to sign in?
This can is a common problem, be sure to check your connect to the internet