Finding a stroy
Hi
Yes, this problem has happened many times to me and it will happen again. First advice is pick up a book called The Artist's Way, it is a recovery book for all Artist's. The main ingredient is writing each day, this should bring new ideas to the table.
Now I doubt that you have nothing to say, there must be something in your daily life that sends a flash or something that grabs you as a story to tell. This is the trick as a filmmaker or writer find the story that resonates in your bones. It could be a documentary, a narrative or a short film. I recommend starting small first, film making is a labor of love and is very expensive. Remember: Story, Story, Story is the key.
I hope this was a help?