Recordbox collection is completely empy after Time Machine restore

Hello everyone,

I hope someone can help me.

Yesterday I used time machine to 'go back in time'

Now suddenly my Rekordbox 5 collection is empty.

So no tracks are visible in my collection and no playlist.

See the picture below

Any idea how i can solve this?

( All tracks are present in my music folder, though the last time I did make a "backup Library" is long ago, because I make regular time machine backup, so I think/thought that that is/was not needed..

(To make my story more complete: I'm in the process of moving Rekordbox to a new macbook, for that reason I changed the user name of my old macbook, into the same user name of my new macbook. Though then i did regret renaming the username (because i was afraight of too many complications with Rekordbox), so then I decided to FORMAT my old macbook, and to use time machine to go back just before I renamed the username yesterday.

Yesterday I did format my old macbook to APFS .. i'm not sure if that would be correct (my new macbook is also APFS formatted) I think before yesterday it must have been another format then APFS because my old macbook is from 2012