It's never happened to me. You see, I have this crazy thing I do - it's called READING. I find it to be quite helpful as a source of ideas. In fact, I accrue so many that I'm forced to write them down on scraps of paper or to save them in draft e-mails to myself. Then, when it's time to begin a new story, I sort through all the ideas I have and see which ones might be the most promising for forming the skeleton to a plot. And if something comes to me in a dream, or if I come across something in a conversation or see something on television or wherever I might get a bit of inspiration, I'll add that to the pile as well. But the ideas primarily come from reading.
If you don't read - and read a lot, you're not going to have a variety of different ideas at your disposal for whenever you might be in need of one.