This Statement off the web I am quoting from the web will help you to understand it better.

"The reasons for your block may vary, but some common ones includ

Timing: It's simply not the right time to write. Your ideas may need to stew a little longer before writing them down.Fear: Many writers struggle with being afraid, with putting their ideas (and themselves) out there for everyone to see and critique. Fear is a major reason some writers never become writers.Perfectionism: You want everything to be just right before you ever put pen to paper or touch a keyboard. You try to get it perfect in your head and never do"

Here are some solutions from the web I am quoting that may help you to break free of Writers Block!

"Go for a walk.

Do something to get your blood flowing.
Read a book.
Freewrite.
Listen to music (try classical or jazz to mix it up).
Brew some coffee 
Create a routine. Many famous writers have daily routines to summon the Muse.
Spend time with someone who makes you feel good.
Call an old friend.
Brainstorm ideas in bullet points.
Read some inspiring quotes to get you started."

Every writer will visit the Community  called "Writers Block" where all writers visit at one point in their career.  Some come and leave after a short visit, while others stay longer.  It's nothing to fear as you have many residents there that you can chat with and discover what their writers journey is all about, and what brought them to the neighborhood.  You will make friends and discover you are not alone.  So enjoy your visit, make friends, hear other writers stories, and tell you own too, you won't be there forever!

For myself I find that I overcome it by just writing on different things, leaving my  work in progress for awhile and doing other writings , not pressuring myself to complete a book until I feel inspired to go back to it.  But Never stop writing, write something everyday!