to install youtube app on iphone 4?

My bf jst removed my youtube app on my iphone 4 not knowing how he did it, but I cant seem to find a way to put it back on my home screen. its in my multitask bar and everything but it dosnt let me drag it to my home screen. what should i do? i already tried plunging my phone into itunes to get the app but its not even there as well

There’s only one other trick I’ve seen.
Go to Settings > Restrictions and click on "Enable Restrictions"
You may be asked for a four-digit passcode. Enter one, then enter it again when prompted (REMEMBER IT!)
Scroll down to the "Allowed Content" section and click on "Apps", then select "Don’t Allow Apps".
Back out to the main screen. Turn off, then re-start your phone.

Go, again, to Settings > Restrictions and click on "Disable Restrictions"
You’ll be prompted to enter the 4-digit passcode again.
Return to the main screen and hopefully the youtube icon should be restored.