how can I restore my photos

[EsTaF]

Hi all
A few days ago I saved my entire photo library using Lightroom's catalog save system to an external drive with that manual.
Then I reinstalled windows and tried to restore the library but after it I'm watching a message "The file could not be found".

Where did the program save these files?

[Per Berntsen]

The photos are not in the catalog. The catalog is a database that contains the edits and other metadata, with references to the photos and their location.

LrC doesn't save the photos anywhere, it can only save catalog files.

So did you back up the photos before reinstalling Windows, or do you have a backup from previously?

[EsTaF]

No, I didn't.  In my opinion, a backup is a backup. Very "good".

[Per Berntsen]

It says quite clearly in the backup dialog that your photos will not be backed up.

If you have no backup of the photos whatsoever, I feel sorry for you.