Sekiro uses one profile-level S0000.sl2 file, so a file replacement can roll back several in-game slots at once. The safest routine is therefore simple but strict: close the game, copy the whole account-ID directory, keep more than one dated generation, and only then experiment. Steam Cloud is another revision source; if a manual restore appears to revert itself, solve the synchronization conflict before overwriting the folder again.
Start with the least destructive explanation
When Sekiro: Shadows Die Twice progress appears missing, first verify the active PC location: Windows: %APPDATA%Sekiro<user-id>S0000.sl2 | Linux / Steam Play: Steam Play: <SteamLibrary-folder>/steamapps/compatdata/814380/pfx/. Expected files/folders: S0000.sl2. Many apparent save failures are actually profile, storefront, path-redirection, or cloud-selection problems rather than damaged game data.
Preserve every surviving copy
Copy the entire Sekiro account-ID folder with the game closed. Keep multiple dated versions because the game continually updates the same container. Before renaming, moving, replacing, or opening candidate backups, copy them outside the live directory. Do not use the only surviving file as the test specimen for repair or editing.
Check launcher and cloud state
Storefront context: Steam. The user-ID directory is part of the save context. Do not assume a copied S0000.sl2 belongs to the active Steam identity. Cloud notes: Steam Cloud is documented. A sync client can reintroduce an older or newer version after a manual restore, so recovery work should keep local and cloud copies conceptually separate until the wanted progress is confirmed.
Use format and compatibility clues
The Steam PC profile is a single S0000.sl2 container under an account-ID directory. Multiple in-game slots are not separate operating-system files. One .sl2 container can hold multiple in-game slots. File-level replacement rolls back the profile container, not one isolated character slot. If the file exists but is ignored, compare the complete directory structure, slot/profile naming, game edition, mods/DLC, and any companion metadata. Do not assume an extension change or generic checksum tool can repair a game-specific container.
Game-specific troubleshooting
If a restore is replaced on launch, compare Steam Cloud state and modification times. Keep the original local file before testing any imported container. If a known-good backup works, preserve it and create a fresh in-game save before further experiments. If no copy works, prefer read-only inspection and source-backed game-specific tooling over repeated writes.
Verification context: Windows path, S0000.sl2 filename, Steam Play behavior, and Steam Cloud support were reviewed against current PCGamingWiki coverage.