Your dog/cat/fish/other pet is always tired when you get home at the end of the day. What is their day job exactly? What are they doing?
Describe your character's death in 1st person POV.
All of your toys come to life at night (regardless of whether or not you are asleep) and hold meetings under your bed. What goes on at the meeting?
Write an angry letter.
Write one sentence every day. Where will you story go with that much time between thoughts?
You were sucked into the last book you opened. What is it? Are you happy about it? Are you scared? How do you get out? Do you get out? How were you sucked in?
Create found poetry by flipping through radio stations.
Set a timer for 30 minutes and do not let your pen leave the paper. Write whatever comes to your mind.
Write a character sketch for a house.
Create a dystopian household.