The notes dispeared , there is only the default welcome note. The .config folder was accidentally deleted , but the main Joplin folder still exists without modification or deleted files,
I'm new to Joplin and haven't made sync yet,
Is there any way to restore notes ?!
How was the config folder deleted? Is it possibly in a trash bin?
As you may have figured out, the notes are stored in the config folder. Since you didn't sync (and didn't mention taking any backups) recovering the .config folder is your best chance.
If you didn't back it up, take an export, sync online, it isn't in your recycling bin and you can't restore it with some kind of data restoration tool then you are out of luck I'm afraid. How did the folder get deleted in the first place?
The .config\joplin-desktop folder contains everything for your local config - notes, resources, settings etc. Anything else on the system is just temporary stuff or program or installation files.