How do i know what do i want to make and how do i give it phizical shape?

I always wanted to write a story, to make an animation, make comics, etc, but now that i have a lot of free time i can't come up with even one single ideea.
My drawing used to be random antropomorfic characters wich just came in my mind out of nowhere. Now i only draw humans.
I have never wrote a story or a backstory to a character. And the few wich have a bit of story seem like having no purpose.
I ahould begin with a setting, a theme, and a plot. But from where do i find them? How do i come up with them? i could watch a movie and create an ideea but it wont represent what i want to make, it would be its own simple daydream.