I'll give you a Zen answer, since it's in my damn user name: "Inspiration comes when you don't look for it. Only when you're open to it."
Sounds counterintuitive, but hear me out. I'll give you a few examples.
Once, I was struggling to write a story for a magazine that was having Open Submissions. Wracked my brain about something to write, but nothing came. Finally, around midnight...I gave up, went out onto the patio, lit up a big fat one and took a few tokes. Suddenly, a weird "What if" premise came to me and the bones of the story formed within a few minutes. The next morning, I wrote the story down, polished it up and submitted it. It was my first professional sale.
Another side gig I have is as a session guitarist. People send me their songs and ask me to add tracks. A buddy of mine sent me his song and told me he was envisioning the guitars to have a certain vibe. So I listened to the appropriate artists and tried to come up with something similar to that vibe. But nothing worked. Finally, I gave myself a day off from the project and did other stuff. When I came back to it, I just jammed out to the track and listened to the playback. I found the kernel of an idea that I developed into a full blown riff and solo and laid it down. That worked even better and my buddy was satisfied.
Finally, I read a story not too long ago about one of the concept artist who did the majority of the work for Fallout 3 (I forget his name). He passed away a year or two ago, so this was a retrospective of his career. The article said he always found inspiration in random things. One example stated that he was asked to design a type of gun, so he looked at small kitchen tools (egg beaters, knives, etc) for inspiration. He would intentionally NOT look towards the things he was designing for inspiration. I thought that was a brilliant approach. And to tie that in with my previous example. If someone asks me to provide a metal track to a song, I'll listen to country or jazz for inspiration, etc...
Anyway, hope some of this helped. Good luck!