I want to not return a backpack I took
Why steal a backpack in the first place?
I was a bit out of my mind at that point in time
Stealing is wrong. Even if you were out of your mind, it is not right. Return the backpack to where you took it from.
Nope, I'm not returning it. I dropped it on the road anyway.
Do not drop it on the road. If someone were to return something of yours, you'd want it to go to you, and not on a road.