Every writer claims to have writer's block, some say it is a myth, as teachers don't get a setback where they can't teach, or a nurse can't help the sick.
If this happens to go for a walk, brainstorm, but a really effective method and will help your story. Put some distance from your story.
1) Write ten things that might happen next.
2) Write ten things that will absolutely not happen next
3) Write ten things that are wrong with your story
4) Write ten things that are right for your story
5) Writer your character's motivations
6) Write all your characters fears
7) Write a letter to your character
8) Get your character write to you like a penpal, they tell you all about themselves.
9)Brainstorm bullet points
10) Best of all for overcoming writer's block is to write. Freewrite about anything.