An ounce of prevention is worth a pound of cure (even in metric).
I experienced over two month’s of writer’s block many years ago. I did, literally, sit at my desk for hours, and can to this day accurately describe that desk. Its vision is before/behind my eyes as I key. It had a red leather surface, boarded in black. It was of thick mahogany with drawers. It faced the wall not far from the door to the room. I have placed it in one of my novels.
To not have this debilitating situation happen again, I have devised a scheme that I find is 90% successful in combating writer’s block.
Do not finish your thought on page or screen. Make sure it is solidly in your mind (make notes if necessary) but do not write it down.
If it’s a description – don’t finish it.
If it’s dialogue – don’t complete it.
If it’s a line of poetry – don’t end it.
The next day, start off with the phrase you would have ended with yesterday. Read the preceding page or two, and when you enter the phrase not completed, the odds are excellent you will continue on your way.