Perhaps not a useful suggestion, but I tend to try to start with the hook. I just keep rolling things around in my head until I have one sentence that sounds really good, and then I elaborate. I rarely end up changing this sentence once I write it. When coming up with story hooks, there are a few basic elements you can think of: your character, your setting, a problem, and additional details. An example could be "The porch steps creaked under Amy's feet when she finally got back, hours later than she had promised and soaked from the rain." We have a character (Amy), a place (the porch), an immediate problem (she was supposed to be here sooner than she was), and a detail that could be elaborated on (she's soaking wet). So then my goal is to start figuring out more about the setting (is this even her house?), the character (how old is Amy? What was she doing?), and the conflict (why was she supposed to be here by a certain time? Why was she late?).
Not every story hook needs every single one of these elements, but if you're stuck, you could try just starting with any sentence that contains a few of these and go from there. I also don't sit and think about this formula when I write, it's more so that when trying to break down why starting with the first sentence actually works for me, I notice that the first lines of my stories do tend to contain this information.
And I'll also share one of my favorite writing prompts, which is to write a story about a character whose actions and thoughts contradict each other. I like this one because it means that, by default, your character has an internal struggle, and there's a lot of ways to interpret the prompt. It could be someone who feels like they have to do something they don't want to/something against their better judgement, or it can be an unreliable narrator who thinks they're behaving well or behaving badly when in reality it's the opposite. Another good prompt is to write about a character in a setting where they are expected to feel one way but instead feels the opposite (i.e. someone who is happy at a funeral).