“Writer’s block is just a fancy way of saying I don’t feel like doing any work today.” ― Meagan Spooner
A tad harsh? Probably.
I don’t know about Writer’s Block, but I do face writing challenges. A gaping plot loophole that you can’t find a fix to, dialog that works so much better in your head than on the computer screen in front of you, the challenge of creating a setting that can transport the reader into the world you are building. Some of these issues can take days, weeks to resolve. There are days when you sit in front of the laptop (or with a pen and paper) and hours pass by without anything happening.
What helps me (but does not avoid the problem altogether) is to have a broad outline of the story and a sequence of main events spelt out at the start. Though the characters evolve when you start writing and do not stick to the script, like errant actors bent on improvising, the existence of a broad story line helps you to get back to core of the story you are trying to tell and hence can be a helpful navigation device when you are lost.