Shop page blank

My shop page is blank, while the dropdown menu under the shop works perfectly. These are the product-categories. But on the shop page, there should be an overview of all the products of all different categories.

It went wrong when i started to change the permalinks in Settings -> Permalinks. I changed the product-permalink-base. Now i’m not able to change it back, it goes automatically to ‘custom base’ after saving.

So something is wrong, who knows what it is and what to do to solve it?

—
After the change in the permalinks and a lot of tries, i deleted the ‘shop page’. Later, i went to Woocommerce -> System -> Tools to get back the deleted woocommerce page. It was there again, but it seems it’s not recognized as the shop page.