Here are over 300 writing prompts to get you writing. They won’t all lead you to your next big idea, but they’ll get you writing, and that’s always the first step.
Another great way to inspire yourself: Watch one of your favorite movies. Try to view it from a slightly different perspective. Try getting into the mindset of one of the side characters. When you’re done, look into that character’s future or past and create a narrative for them. See where it takes you.
One more: Watch a movie that makes you think. Sit and ponder with a keyboard in front of you once you’re done watching. Write down the big ideas and the little epiphanies that strike you. See what story concepts or themes of interest emerge.
Just keep writing.