Sometimes you just need a little inspiration to get you on your way.
The task of writing can be quite daunting. Whether you are going to tackle a short story, or trudge your way through a novel; either way, you will have to begin your journey somewhere. For me, at least, beginning my own universe can become overwhelming, but once I begin, the ideas flow out in a random spattering of thought that I then have to sew together. Of course, everyone's process is a little bit different, but here are some ways I have found I can always get something started when I don't know what to do.
Browse Books that Fall Into Similar Genres as Yours
If you don't have time to read, you don't have the time (or the tools) to write. Simple as that. -- Stephen King
The first thing that I have always done when deciding to pursue another writing piece was determine a broad genre that it'd belong to. Of course you can simply search Google for "book genres" and you will have plenty to choose from, but I find reading books for several genres helps you determine if that is truly what you want to work with, or if you want a slightly different genre. Every genre has some sort of tone that follows, and in most cases, you will have many tones in different pieces as they approach the same theme with a different method. This might actually persuade you to try a genre you've never considered before.
Read Books of Similar Styles to Yours
Do you write in the first person? If so, you might try finding books or short stories that have the same approach. Or do you have a rather unique sense of humor? Try searching for various comedic authors until you find one that is similar. This can help guide you on how to incorporate your talents into a wonderfully assembled story!
Draw Character Inspiration From Multiple Different Books
Remember, the essence of storytelling demands that we place our main characters on a path. A quest with something at stake, with something to do, to achieve, to learn, and to change. -- Larry Brooks
Before copying character traits down, remember that your characters will have their own journey - one unique only to your story. However, drawing together traits from characters of multiple books can help you with a starting point. You are creating an entire person when you create a character. They have a backstory, complex feelings, and different circumstances that make them who they are, which all of these factors will be unique to your story, however, finding basic traits from other characters is a good start. I often find myself thinking, I want a mix between this and this person in how they act, and it is a bit easier to go from there. You can come up with the reasoning for their traits later.
Start Jotting Down Ideas
At this point, you will have found some sort of setting, character scheme, or idea that struck you from your time reading other works. No matter if you feel you're completely ready or not, set some time to just start writing the things you know you want to include. Those will lead you to a couple more ideas, which will lead you to more. This isn't to say you are copying someone else's work (because that isn't where I am going at all), but you can recreate the same feeling you felt when you read some other story, only with your own plot, characters, and message. Just write away like there's no tomorrow! Good luck!