This is just my humble opinion. You can write your own blog if you disagree and tell us your story after reading my observations and suggestions.
Here's how I see it. I've had the inability to move forward with a story; sometimes for weeks, sometimes for months, sometimes for years. That's not writer's block. It's a problem with the plot or characters or your motivation. Writing is often work--hard work. That means working through the problems of a story. Not just spitting it out and expecting that all it needs after it's written is a comma or two in edits. Most stories take at least a little analysis.
What people believe is writer's block is actually a point when the writer loses direction or interest and tries to force the story. Pantsers or plotters may need to take time to regroup. A plotter will write out the plan or draw a diagram; a pantser will imagine the solution while running or cooking or staring at the starry-night sky. Sometimes it takes minutes, sometimes months for the solution--the ah ha moment--to strike. Sometimes it doesn't ever come. Why? Because you're trying to fit a square peg in a round hole.
That isn't writer's block. It's a convoluted premise. You imagine the story plot and the characters. The characters don't always do what you think they will. Why? Because of plot flaws or character flaws. When you fix one the other will fall into place.
Other reasons writers think they have writer's block is because they
1. don't like the plot or genre they've chosen to write
2. don't know their characters, especially the hero/heroine
3. can't fulfill the story promise
4. don't know how to fix it
Ask yourself if it's one of these issues. Be honest. What don't you like? Get to know your characters better. If the plot isn't headed in the right direction, maybe you need to look for another way to get to the end. In the swamps? Don't know how to get out? Read a book on craft. Ask a critique partner or trusted reader to review what you have so far. Talk over the character or plot problems with another writer. Don't feel like you have to follow every suggestion. Sort through them all and find the ones that will help you get past your story's sticking points.
If you still don't come up with a solution, it's best to move on to another project. You have them. Let the other book simmer. Sometimes it will come to you later. Go through your other ideas, preferably the ones that intrigue you. They exist in a phrase you wrote down on a napkin, a title running around in your head, a line from a movie you can't shake, an impression of a scene you need to write. If you don't have anything. Change it up--read a book, watch a movie, listen to music, do something different until you find that something. Most of all, even if you're on deadline, don't force it. It's the pressure to write something concrete that stifles your creativity. You think proposals are just that--concrete. Synopses often change when the story is written. All because your experience changes, and how you feel, at any given point, is different. The longer it takes to write a book, the bigger the change.
Personally, my career in writing has changed in the last twelve years because I've gone from being a student of the craft to a teacher. Ten years of writing experience and editing has given me an insight I didn't have in the beginning; so my vision has improved and is continuously adjusting. Gemini was a project I began working on many years ago. I shopped it around and had some interest from publishers, but back then no one wanted to commit to publishing a series. Authors didn't want to write them for a variety of reasons, and those who did took a risk. My goals changed, my voice changed, my knowledge grew. I stopped writing the Gemini series after doing a proposal for five books; completing the prequel and the first book and beginning the second book. You could say I had writer's block but, in all honesty, I love this series more than anything I've ever written. Why would I avoid finishing it?
Pressure. I want this series to be read. I don't care if it makes money. I want readers to enjoy it. Talk to me about it. Interact. The industry has changed since I wrote that first book in the series. So now I have a plan and patience.
The prequel will release May 28, 2017. It's going on Presale March 31st. Sign up for my Newsletter [http://eepurl.com/buCZLf] and I'll send you the links of where to buy The Gemini Mythology when it's available. I'll also have a contest to give away a few copies to five lucky winners on my website at Eliza March. If you're a fantasy fan of faery lore and mythology, keep your eyes open for Gemini at all major ebook sites and help me reach my dream. Tell your friends about it.