One day, Pinkie Pie wakes up with a headache. The night before she spent a lot of time partying late into the morning and she must have somehow blacked out. She cannot remember what happened but is desperate to find a tray of cupcakes she took with her to the party. These cupcakes weren't intended for the party. For you see, these were very special cupcakes that she simply had no way of dropping off somewhere safe with enough time left over to make it to the party.
As a result, she took the cupcakes with her. Unfortunately, she seems to have misplaced them. She recalls something about one of her friends borrowing them and a pinkie promise to return them to her in the morning. The lack of cupcakes by midafternoon has made her very upset. No one breaks a pinkie promise.
EDIT: CONCLUSION COMING SOON.
Lol... ok, this story is just a silly wild-goose chase with cupcakes!
I like how you present the characters. I think you're clearly showing the personalities of each characters pretty well. 
I am going to track this story. I can't wait to see what's going to happen next. 
Side Note: You definitely need to fix some grammar mistakes and a lot of punctuation mistakes! If you need help with some of that, I don't mind giving a hand!