Root folder/subfolders not shown, only last used folders

Lightroom Classic  v9.1

The root folder and the subfolders are no longer shown in Lighroom but all folder are still at the disk. Only the last used folders are shown in the library tab. How can I switch back from "last used folders" to  "root/subfolders". 

I have not done any setup changes myself, LR just changed the way to show the folders. Now I cant open most of my files because they are not located in the last used folders.