C:\Users\<user>\Graphisoft\TW Data

[Anonymous]

When I click on the save button, i understand it saves a local copy in my pc in a default folder : C:\Users\<user>\Graphisoft\TW Data
but when I go to that directory, I find a lot of files, but no PLN or an archicad file..
how can I use this back up to restore my work?

[Laszlo Nagy]

There is no PLN there because it is in database format used by the BIM Server.
You need to use the Rollback function in the BIM Server Manager to restore previous states saved as backups.
For details of the Rollback function see the Help files.