Hello! There are a few things that I've found help me when starting to write, especially something new:
1. Picture a scene instead of trying to plan the whole story at once and then build from there / figure out how to get to that scene.
2. Make a character, you can even base the character off of something you like and then build from there. After making a character you can figure out what kind of world that character would fit into and what their backstory might be.
3. Are there any things that are significant to you? I personally find religion fascinating so my stories tend to have some sort of religious theme to them and that helps me figure out what I want to write.
Basically, just ask yourself questions until you land on something you like enough to want to do! Worst comes to worst, you write a bit, decide you'd rather do something else, and you just go write that something else!