Eeep! Black hole!!

put it aside for a minute, it'll come to you when you least expect it (like at 4am in a dream)
but if you try and force it, it might not come at all

That's so true, I was in a similar position with mine except I had written 80% plus the final half chapter and couldn't see how I was going to make the leap across the void. I turned my back on it for a week and didn't give it any thought at all. During a walk with the dogs, it suddenly came to me so I rushed home and typed it up any old how, just to get the drift... it was relatively easy to hone it over the next few days.

Put the manuscript away for a little bit. Read a book. Start writing another one. It will come in time.

I'm in a similar position regarding the climax of my WIP, how my characters will defeat the bad guy; I'm really not sure how the heck it's going to turn out! So I'm figuratively biting my nails as I near that point.

The way I'm going to do it? Just throw the characters into the mess (taking note of everything that's led up to this point, to keep it logical to the story), the way it would happen in real life--we really can't plan out all our confrontations in advance--and see how it goes. *cross fingers*

When all else fails, you can start asking your characters themselves (including the bad guy) what they're going to do, though I doubt even they could tell you how it'll turn out!

Walk away and do something else. You can even start another story. The brain cells will keep working in the background, then BAM. It'll be there. Happens to me on ever novel.

Thank heavens you squashed the cliche approach. Much better would be to resort to the time-tested deus ex machina to save the day!

In your kind of situation I like to play a game of reverse what-if. I try to imagine the end state scene and final result. Then, brainstorm on what-if regarding the prior scene. Capture those possibilities (no filtering allowed in brainstorming) and do another round. Rinse, repeat. OK, I admit that I don't go very far with the more ludicrous chains of thought, but I usually manage to come up with some workable threads that way.

Oh, like others suggest, I prefer to do that kind of noodling away from the keyboard/pen. Let the muse run roughshod in mental space and try to keep tabs on the different chains that spawn. Almost seems like the extra effort to do that inspires even more creativity and blending.

Best of luck to you.

You could begin an argument between characters. That could get something moving even if you dont include it in your piece.

Put it aside for awhile. But keep writing, just write on another project. It will come.

Everyone's saying to give the draft some space and time, but isn't the solution to sit down and try to write something? Or am I just thinking of writer's blocks?

In my case, more often than not, I have to write something to lure my Muse out of his hiding rather than wait for a miraculous solution.

Just playing devil's advocate.

This is a good thing. Give it some space, but have the problem ticking over in the back of your mind. You want an ending that is both unexpected but true to the story.

I once read of two screenwriters who purposefully wrote themselves into corners. They'd then spend weeks working out how to get out of the corner. That way, they knew that if it took them a few weeks to know what happened next, then the audience wouldn't work it out in the few minutes of screentime they had.