Let me tell you something: ALL WRITERS, OR AT LEAST THE VAST MAJORITY, HAVE EXPERIENCED THIS.
Don't worry. I've experienced this before. This is something many of us as writers face.
But if you wait for inspiration, it will never come.
You must give yourself inspiration. Waiting for it to happen is like getting a train to drive on water. Without tracks.
Now, it's not impossible, but it's very rare and can be considered impossible by many.
I never wait for inspiration, and I have plenty of ideas.
What you need to do is not wait for it to miraculously appear, but instead do anything of the following:
Read books (this can give you inspiration, as you can get certain ideas)
Fantasize (I don't mean the sexual kind of fantasize, unless you are trying to write that kind of book; what I mean is just mess around with a situation in your head) Example: You are pretending to be an elf in your mind. You travel to a land called Bigaspore (or something) and try to save the kingdom there or defeat an evil villain. In your fantasy, you would play the role of the elf and go on the journey, defeating trolls, befriending orcs, and whatever else you can think of. (Feel free to use this idea if you wish)
Look around for ideas (Media, books, shows, movies, plays, etc. are all good places)
Write down a bunch of ideas and put them together in a good way (This is what I sometimes have to do; write down a couple of ideas, then take the parts you like and put them into a story while getting rid of the parts you don't like) Example: I have 3 different stories: a) A girl goes onto a journey to save the race of dwarves from evil elves. b) A father has to travel the world with a phoenix in order to stop a villain in an industrial castle. c) A vulture feeds on the lives of souls, and a boy must go and stop her. Now, here's how I would improve it: I like the idea of a father, and I like the girl too, so maybe it's a father and a daughter. I like the idea of a phoenix companion, but it would seem to fit the boy better. I want the characters to meet, so the boy and phoenix will end up crossing paths with the father and daughter later. I don't like the saving the dwarves, but maybe that can be a separate race? And the vulture could be the villain in the industrial castle that they have to go and stop! (As you can see, I made a story simply by looking at a bunch of different ideas; feel free to use this idea if you want too)
Practice (Write whenever you can, take story prompts and write them, make fan fictions, etc.)
Whatever else comes to mind (boredom helps, since I usually have nothing to do but fantasize.)
You're not a terrible writer. You're just a beginner. I'm kind of at that stage, except I've already figured out how to get past the dreaded Writer's Block. Sometimes, you won't be able to get past that, and that's fine. I have times when I can't come up with anything.
Just don't give up. Practice, and you'll get there.
Edit: I have to add a couple more things:
Sometimes, when I'm looking for a certain story to read, I get frustrated because there's nothing there. So instead of waiting to see if someone else will write it, I write it myself. It also allows me to dictate how the story turns out.
Other times, I like the base of a story idea (dude goes on an adventure to find a jewel), however, I felt like that story could have been different. And then I'll write my own version. Just make sure it's different and you're not crossing copyright!