If I have a HTML mind map, can I import it back into MindManger? I do not have the original.
Not directly, but maybe you can use OPML files or Excel (csv) as intermediate?
And maybe you can drag/drop the content into MindManager.
MindManager does not import HTML exported maps. The content is encoded and cannot be copy/pasted or dragged into MindManager. You will need to manually recreate the content if you do not have the original mmap file.