Joomla 3: how to restore categories?

Question

Joomla

In general. There is a joomla 3.9.21 site which was updated from joomla 1.5

Problem: there is a category tree which is buggy.
1) When you try to specify a parent category, it sees only created categories (does not see "- no parent -")
2) Not all categories see.
3) not all categories allow you to make a parent. Writes: "Failed to save due to an error: Invalid parent ID."

Actually I think it makes no sense to describe bugs.

Actually how to reset/restore categories?
Any method will do. It would be desirable without recreating the site.

Answer 1

I do not think that it will be possible to reset the restore in the current site. If joomla 1.5 remains, try this component https://extensions.joomla.org/extension/jupgradepro/