hmmm...I get inspiration when someone or something really bothers me or makes me think a lot. I watch drawing vids on youtube or look at drawings...that inspires me a lot.
But I don't know...if there's no inspiration then just wait. It will come and you'll draw from your heart. If you TRY to get inspired that's somehow from your mind, not your real feelings anymore.
Inspiration comes itself, I am usually not trying to get any. Of course in some cases like now that I have a school assignment, I think of a theme and try out stuff on paper. I also listen to music trying to get inspired or think of films I like. Of course that can have the wrong result sometimes...I have the assignment "family" and cuz of my twisted nature and inspiration out of Tim Burton and Avenged Sevenfold, I am now drawing a macabre familly of dead people :P
I asked, that subject doesn't get grades...The teacher actually liked it, she thought I was trying to pass a message about how rotten todays society is blah blah blah XD...I am just twisted :P
I often have the same problem, but try drawing something you've already drawn, and maybe try and make it better than the original. Or look at your past drawings, read a book, watch a film. I also find that it helps tolie down and listen to music, or just imagine drawing something in my head. This often gets me in the mood to sit up and draw, and then I should be able to just draw anything.