Write about your everyday life. This will keep you (or get you back) in the habit of writing more often, and get you moving again. You can even write about how you're feeling stuck in your writing, and maybe ponder why. You might find the answers you've been looking for.
Writing down your dreams will get you back into the habit of writing, and often give you some unexpected inspiration.
Try drawing your characters, or settings from your book. They don't have to be perfect, or even true to your fictional world. You might find inspiration by drawing something a little off--how might that scene you drew happen? Drawing will also keep you in your fictional world while stirring up your creativity again.
Maybe drawing isn't for you--or maybe it is. But either way, coloring is easier. Put on some music and chill out for a bit. Especially if you've been banging your head against the wall trying to conquer the blank page, coloring is a great way to let your mind unwind while still keeping a little bit active.
Write or draw with your non-dominant hand
Weird suggestion, I know, but trust me. You'll wake up parts of your brain you don't normally use. Who knows what else is in there?
Again, a good way to get you in a creative mood. Plus, how long have you been sitting still staring at your computer? Moving your body will do you some good.
I'm an acapella girl, of course I'm recommending this.
Try something new—take a new class, join a new club.
It'll wake up your brain, and help you shake out of your funk. Who knows? Maybe you'll learn something new you can apply to your main character.
Read--or read your own work out loud
When all else fails, it's time to hit the books again. Read, read, read, and when you take another look at your own work, maybe try reading it out loud instead of skimming it quickly. You're sure to find new things when you not only look back on it, but hear it spoken.
Best of luck to you!