Ipad is locked

Well i was opening the youtube app when suddenly my ipad stay locked on the Youtube icon. I can't do anything now, like i can turn off my ipad but when i want to turn it on it kind os goea back automatically on youtube. A few minutes ago, i could use Siri but i can't amymore. And i hope you could help me unlock it simehow.

My Ipad is quite old i'd say 3 years if my memory serves me well and it's, according to the info behind it, a A1458 so a 4th generation. I don't know if i can provide more information.

Thank you.