Most writers have lacked good ideas at least once in their careers. If you've been out of ideas for awhile, it's even worse. It also doesn't help when the fantasy and science fiction world is inundated with copycats and stories that sound like many others. But a "lack of ideas" isn't permanent and shouldn't be. You can control whether you have decent story ideas or not.
Here's the secret: to get a good story idea, you have to come up with a lot of bad ones. You do that by writing, continuously, even if you think it's no good. In the midst of the so-so ideas, you will find something worth working with.
I used to be terrible at running. In fact, I hated it. Every time I tried to run, I ended up gasping and wheezing while trying to massage the cramps out of my legs. But my husband encouraged me to keep trying. "Just two more minutes," he'd say during our workouts. "Two more minutes and you can slow to a walk." Every day, I ran two, torturous minutes longer than the last day until, one day, I ran and...kind of enjoyed it. Or at least didn't die after it. It had taken hours upon hours of painful mistakes to get to that point, sure. But, if I hadn't started, I would still be wheezing after the first two minutes.
The same is true for writing. It might not look or feel pretty when you spew random ideas on paper (and, yes, they probably won't even be all that original at first) but that's exactly where you will find the gems that you'll want to keep.
So, in reality, this isn't just about ideas. It's about discipline. We have to write if we want to move forward. Even when we don't feel like it. Once you've dedicated yourself to that, the good ideas will come.
Take some time today and write down your answers to the following questions:
What is the coolest gadget that you can imagine? (Or, alternatively, what is the coolest places that doesn't exist that you can imagine?)
Now, what is the scariest or most unusual way you could kill one of your characters?
List 20 ways to kill one of your characters with that gadget (or kill them in that place) that you just thought up.
It doesn't have to be death and destruction if that isn't your thing. It can be 20 ways to save the princess of your fantasy world or 20 ways to make contact with an alien species. Use your imagination! The point here is that you want to get your mind moving.