Hi I overwrited the ‘Welcome Notebook’ for my first notes. After installing Joplin on another computer, all my notes were overwritten by the ‘Welcome Notebook’ of the new installation, it seems Joplin considered the ‘Welcome Notebook’ of the new installation was the ‘last moded’ versión of the Note.
Take a look at this dropbox article. It detailed how to recover older versions of files. To get the filename you need you should right-click on the file you want to recover, select “Copy Markdown Link” and past that somewhere. The random bunch of characters between the () and after the : is the filename you’re looking for. I hope you can recover your data!