Sometimes, I don't feel like writing. I just don't want to. I love writing, so there's usually a reason why I grumble as I plop down in the chair without enthusiasm. Here are my reasons, and what I do about them.
Fatigue is the creativity killer. Many of us have other jobs, and most of us have other obligations that require our attention. And I hear you, devoted writers who say that you make time for the things that really matter to you. That is true. But most of us are pulled in many directions at once, and you do have to make choices.
When my problem is fatigue, I choose rest. Not the two week kind, but a few hours, maybe overnight if it's been really rough. While plenty of pantsers wander in their plots, I don't like to, and when I find that things are just randomly happening to characters, or I'm describing the process of tying shoes in great detail, it's time to rest. My readers don't want to read that. I don't want to write it. It usually comes from fatigue, and anything I write in that state will wind up cut anyway.
2) Wandering Plot
See above for the cause of this problem. Once I've let it happen, I find it hard to keep writing. I don't want to throw out pages of work, but I don't want to keep going as if I haven't noticed I've gone off track.
This one requires the courage to throw it out. Go back to where you lost the thread, and start slashing, metaphorically. It will hurt, but when you go back and start that scene over, it will be better, and you will feel better as a result. It's cleansing to let the shoe tying go, and return to something more interesting.
If you're bored with your story, chances are good your reader will be, too. When were you last enthused about it? Find that spot, and consider what would have happened if that character had gone the other way at a metaphorical fork. Or maybe a physical fork. Is it possible to make a better story that way? More conflict?
Sometimes, too, it's a lack of detail. You don't want endless descriptions of a window frame, but you do want to know whether it's wood and glass, or just a hole in a stone wall. Make sure you've thoroughly painted your scene, so you can see your characters moving through fictional space and time. If you get into their worlds, you will be more embedded in your world, and you can take your readers with you.
These are my solutions to sudden and overwhelming indifference to a project. Have you got another reason for your indifference? What do you do to alleviate these problems? Let me know - let's talk about it.