Please correct my sentence if you find any mistakes or if they sound unnatural.
Today, I had a lot of to do so I’m tired.
in the morning, I got up at 8am.
It was pouring outside so I was supposed to take a walk.
This part doesn't make sense. Did you mean; I was supposed to take a walk but it was pouring (so you had to change your plans?)
then, I was watching English stuff on YouTube so that I would learn English.
My father called me out of the blue.
I something urgent came up so I left home as soon as I got ready.
"something urgent" is the subject here, you need to delete I.
Anyways, I just got back right now.
Choose one of just and right.
I had a long day today so I’ll go to bed early than usual.
I’m done for today.