I have had that, yeah.
Usually the reason I don't feel like writing is because I get sick of whatever book I'm writing, and can't feel like I like it anymore; and it's not fun to write about something I don't like.
Usually the way to get myself to work again is to find something, any kind of thing, that I really like, and write about that: maybe a color, or an animal, or a strange fairy-tale. It ends up making me not feel bad anymore, and then I can go back to working on the book I was working on. Or I might put the color or the animal or the fairy-tale into the book, and that works too.
Or, I might do research, and that is fun.. or I read another book that is a little bit similar to the book that I'm writing, and that makes it fun again because I start liking it.. or I might look at pictures, or dance, or whatever. I do something fun, and it cheers me up, and then I write again.
You might not have the same problem as I usually have, so that might not be helpful for you. But it could be helpful maybe.

Lady Eliana wrote:
I have a couple of different methods and I'm not sure which is better or if any of them really work.  One is that I just keep writing, even if it is forced, knowing that I can edit later.
That works too, when I really have to.