Same Problem with me,
Recently someone enabled the multistore function from back office for my shop.
i manage to disable the multi-store option, but what actually happened is horrifying, every product on my shop become out of stock in ongoing promotion, i manage to import the product csv file for increase the quantity which i saved before. Today i have notice one more thing that i cannot access categories from back office and also from front end.
Category structure is like
Home - Shop - Men Fashion - Sub Categories for men fashion
I can access only shop but when i click on men fashion it through me back to root category page or whenever i try to edit or delete the men fashion category it again through me back to root category page and does nothing.
any help would be appreciated.
Thanks in Advance