No writer likes talking about the dreaded staring-at-blank-screen moments, especially when those moments stack one upon the other for days or even weeks on end. Some call it writer's block. Others pretend it doesn't exist and still others take it as a sign that they no longer have anything to write about so they stop writing all together.
I usually don't have deadlines to write by, so I basically ignore the dry spells and find other things to do, but I've been writing long enough to know the enemies of my muse.
Sleep, or lack thereof, can muddy a muse beyond functioning. I read an article recently that stated women have more issues with sleep deprivation than men, so my issue with it may not be such a problem for others, but it's my biggest enemy these days. It doesn't help that I'm also a night person. It does not matter what time I go to bed, if I try to make my brain function before nine or ten a.m., I'm useless. My imagination gets blocked out and locked behind the desperate fog of doing anything else that is required of me. If the muse has vanished, try to respect your natural sleep cycle as much as you can and catch up on any hours lost.
Life has a way of dumping difficult things on us at random times. We have no control over this, only over how we handle it. If something worrisome arises, I have to work harder to get into my zone and make contact with the muse. For me, it takes good music and some time to block it all out. If worry plagues you, find your coping mechanism, be it music, a favorite meal, a trip to a favorite place, whatever it is that helps you escape the worry for a little while.
Stress is related to, but not the same thing as, worry. There are different kinds of stress and all of us deal with it at one time or another. Having an unfinished job hanging over our head, a sick family member, household demands, demands of a job, you name it. The typical ways of dealing with it, deep breathing, relaxation techniques, calming music, aromatherapy, all can help. Find what works for you.
There's also a little side note about stress, depending on what it is, it can actually fuel your muse. So only try to escape the stress when it's blocking your muse.
There is no escape from this one. Whether it be walking the dog, running the kids to activities or doctors, or working a day job, it must be done. The key here is carving out time to write when you can. I also work over plots and scenes in my head while in waiting rooms or waiting for the kids to finish an activity or even while grocery shopping. With responsibilities, the key is finding a way to work around it. I once even worked out the details of characters for a book on the back of a grocery receipt while waiting in the car with my middle daughter. Do what you can when you can.
Time is a precious commodity these days, it seems. There really is no easy fix for this one. As a writer, you have to carve out an hour or two every day - or whatever schedule you can find - and make it work for you. The important thing here is that you find the determination to make it work for you. So the key to keeping this one from murdering your muse is to carve out those hours anywhere you can.
I'm not really a good one to give advice on this. My issue here is the opposite. I have too many ideas all rattling around in my head at any particular time. But I still have to work to find what one can work for what story. My secret here is to focus on the characters. Once a character is created, their personality will point to the idea and story they want to star in. My other advice for this one would be to just write. Pick a persona/character to think in and write down whatever comes to your mind. Then see what commonality all the jottings have and explore what type of tale it would best serve. Give yourself the freedom and permission to write freely without anything like "it has to be done this way or that way." Just let it be and explore. Writing so freely will often jolt loose some really fantastic things.
Not all writers need to be motivated to write, but it's been my experience that the best writing comes from motivated writers, not just writers who force words into a computer. Writing is barely ever topnotch until a lot of blood, sweat, and tears are shed to mold a first draft into gorgeous writing, but the spark that ignites the first draft will catch on better if the writer has the right spark under the muse. How we each find our motivation is unique to us. For me, it's finding the right music, a dark room, candles lit, and incense burning. I do everything I can to help place myself in my imaginary world and write my characters as true to them as I can.
This one is also a very personal thing. It does not matter if someone has written no books or twenty books, fear of failing with the next one can leave the muse locked in a deep dark tunnel, unable to shine. Determination is the answer to this one. No one is perfect, no writer will do it all just perfect. All we can hope to do is write the best story for readers we can possibly write. So learn your craft, give it your best effort, and accept that your best is great enough.
In closing, writing is hard work and a writer has to be willing to put in the blood, sweat, and tears to accomplish their tale. It's not an easy get-rich scheme. The creation of a novel takes effort, getting it into print (or electronic print) takes more, and the marketing of it after takes even more. But if it's in you to write, you'll find a way.