I can't unlock my iPod 5th Gen, please help!

Hello, I am having really a trouble now, it was just this morning 7 hours ago.
I had just fully charge my iPod 5th generation by using a power bank . I turn off it for a seconds to close the screen. and then seconds after it wont work anymore !, it wont work the "slide to unlock", until now. But the circle one its still work . I really wonder if its because something wrong on the screen ? but if its in the screen why is the circle button it will work. The really big problem is that until now I can't unlock my ipod.. pleaseeeeeee helpppppppppp! :( reallly having trouble!