Updating from iOS 5 to 6 will lose the YouTube icon. You can only get the original version back by downgrading back to iOS 5 but doing this will lose all the new functions available in the iOS 6 update.
This icon is missing on the Springboard (main icon menu) since you updated to iOS 6.
Apple have pulled the inbuilt app from the new updated iOS due to other video apps available and to get the application updated and run by the creators rather than Apple.
The newer version of the YouTube application made by Google has had it features changed and can be downloaded from Apples Apps store for free here:
The newer application also has a different icon to the previous default Apple version that looks like this:
I would like my old YouTube icon back!
How to get it back
me too…it was unique…
R.I.P. YouTube iOS 2007-2012
For some reason I lost my you tube icon on iphone6