Why does no one listen to anything I say at work?

If no one listens to you at work, start with a harder diagnosis: what you say is not changing anything in your environment yet. Being heard is not a courtesy people extend to you. It is influence, and influence is earned by demonstrating that you understand the people you want to move. The fix is not speaking louder or more often. It is doing the work that makes people want you to have influence over them.

That work starts with their interests. Get clear on how each person you deal with is judged, what challenges they are facing, and what makes their job harder than most people would expect. Better, have them help you understand it. Ask them directly what they are up against. When you later present an idea to someone whose constraints you can describe accurately, they are far more likely to listen, because they already know you understand where they are coming from. Ideas from someone who gets it are treated as help. Ideas from someone who does not are treated as noise.

Second, stop presenting your positions as speeches and start diagramming them. Put your idea into a simple diagram, show it to people, and ask what corrections or changes they would make. A diagram changes the conversation. Criticism now lands on the drawing instead of on you, people who would never interrupt you out loud will happily redraw an arrow, and disagreement stops being a fight and becomes information you can use to update your model.

Then notice who is good at correcting you. Some people will turn out to be unusually good at showing you why something is not working or how to make your model better. Give those people credit and positive feedback so they keep doing it. They become your advisors, and a person with visible advisors and a model that keeps improving is exactly the person a workplace starts listening to.