Rebuilding Your Lists:
1. Use your previous (old) notifications to add to your reading lists. (This has been tested and works to start receiving notices again.)
2. If you have any bookmarks -- re-add them to your lists.
3. Use any previous comments (topics) you've left on stories here to help your lists.
4. Use your history (clock icon) to add to your lists. (If you see nothing, click the "Show All" link. It may show something.)
5. If you have a favorite author find a story written by them and start adding the comics listed under their name.
6. If you follow someone look through their lists and start adding to your lists from there.
7. If you have a favorite unofficial scan group -- use their website to add to your list. If they are defunct then use Baka Manga or another avenue to see what series they worked on to add to your lists.

So I logged into my account after idk maybe 3 weeks of not being online and hundreds of mangas i had under reading, want to read, already read ARE GONE
If I search for one I know I read recently and are not in those lists, they still show my last read chapters, but... so many mangas I had saved for later... gone... what can I do to get them back