YouTube not available on iPhone 4?

When I try log in to my account it says "YouTube not availible" I tried logging in on computer and it let's me but just not my phone. How can I fix this?

I no its a stardard annoying answer but have you tried turning it off and back on. I'm able to log into facebook and use it like i was on a computer at the bottom of the page just clicking on standard view instead of mobile view thats all i can really suggest it has worked for me since release.

Apples agreement with youtube for the preloaded app ended. You can now download a free youtube app made by google in the app store. I've found that this new app is actually better