Missing Previews and all cue data after Update to 6.5.1

Hi, all data is missing form my entire 3 years old library.
Data from Explorer folder is vanished, I still see the tracks in folders but there are no Previews waveform and cue data. However track names are same as I renamed it in recordbox. Playlists have Previews and cue data but The File Couldn't be found. (See attached images)

Here is description of all my moves that cause this nightmare. First of all I updated Recordbox to 6.5.1 at Catalina 10.15.4
Then in Finder, I duplicated my 2020 music folder with all subfolders and renamed it to 2021 ( the reason is to save time to create all Genre subfolders) See attached file.

After I started to delete tracks from each folder. Same-time I run recordbox, to create a new playlist before I finished to delete all tracks from new 2021 folder. In Recordbox I wanted to listen tracks from Explorer section in 2020 folder, but suddenly got a message that Files can't be found (interesting that Preview waveform and cue points were still visible). After restarting recordbox previous and cues disappeared. It also affected all other folders as 2019 and 2018. 
Any ideas how can I get all data back? Please help!