Recover deleted files after ransomware without a decryptor

How to recover deleted files after a ransomware attack without a decryptor depends on what actually happened to the data. Ransomware commonly encrypts existing files rather than deleting them, while some strains also remove backups, rename folders, or erase free-space records. These situations require different recovery methods.

The safest response is to stop changing the affected storage device. Continued browsing, software installation, and ordinary computer use can overwrite deleted data and reduce the chance of restoring it. Disconnect the computer from networks, preserve the affected drive, and use a clean device to research the specific ransomware strain through ransomware guidance.

Determine whether files were deleted or encrypted

Start by examining file names, extensions, folder contents, and ransom-note details. Encrypted files may still be present but have unfamiliar extensions, altered names, or unreadable contents. File-recovery software cannot usually turn encrypted data back into usable documents; it searches for deleted file records and recoverable file fragments.

If files disappeared entirely and the ransomware did not securely overwrite the storage space, undelete utilities may locate them. Recovery is more likely on traditional hard disk drives than on solid-state drives because SSD trimming can permanently clear deleted blocks. The age of the deletion and the amount of later computer activity also matter.

Contain the infection before recovery

Isolate the compromised machine by disconnecting Ethernet, disabling Wi-Fi, and removing external storage. Do not reconnect shared network drives until the malware has been removed from every relevant system. Otherwise, restored files or clean backups could be encrypted again.

Before attempting repairs, document the affected folders, ransom note, file extensions, and approximate attack time. If the information is valuable, create a forensic image of the disk and work from a copy. This preserves the original evidence and allows recovery attempts to be repeated without continually modifying the source drive.

Check backups and built-in file history

Look for offline backups, cloud version history, NAS snapshots, Windows File History, macOS Time Machine, and previous versions. A backup is useful only if it was disconnected or protected from the attacker and contains versions from before the encryption event. Scan backup media before restoring it to a connected computer.

Windows shadow copies may contain earlier versions of files, although many ransomware families deliberately delete them. Cloud services can sometimes restore an entire folder to an earlier date, even when local files were encrypted. Practical operating-system guidance and other security tips can help identify which recovery feature is available on the affected system.

Use file-recovery software with care

If no clean backup exists and files were genuinely deleted, shut down the affected computer and connect its drive to a trusted, malware-free system when possible. Avoid installing recovery software on the same drive being examined. Installation and temporary files can overwrite the very data the utility needs to find.

Choose a reputable recovery program that supports the file system used by the disk. Save recovered files to a separate external drive, never to the source partition. Begin with a read-only scan, preview results where available, and prioritize irreplaceable documents instead of attempting to restore every file at once.

Recovery utilities may find file names, folder structures, or file fragments. A file that appears in a scan is not guaranteed to open correctly, especially when it is fragmented or partially overwritten. Encrypted files recovered this way remain encrypted, so undelete software should not be mistaken for a ransomware decryptor.

Compare the available recovery paths

The best method depends on the storage technology, the presence of backups, and whether the data was deleted or merely locked by encryption. The options below have different risks and expected outcomes.

Recovery path	Best use case	Main limitation
Offline backup	A clean copy exists from before the attack	The backup may be incomplete or infected
Cloud version history	Files were synchronized with a protected service	Retention and rollback features vary
Shadow copies or Time Machine	Local snapshots survived the attack	Ransomware may delete or encrypt snapshots
File-recovery software	Files were deleted recently	New activity can overwrite recoverable blocks
Professional forensic recovery	Critical data exists on a failing or heavily altered drive	It can be expensive and cannot guarantee results
Decryptor or key recovery	The ransomware has a known weakness or leaked key	Many strains have no available solution

Know when to use a recovery specialist

Professional data-recovery services are appropriate when the drive is failing, the files have substantial financial or legal value, or repeated home attempts could cause permanent damage. Select a provider that offers diagnostics, clear handling procedures, and a no-recovery or limited-fee policy. Ask whether the work will be performed on an image rather than the original drive.

A specialist may recover deleted file records, reconstruct damaged partitions, or extract data from a failing device. However, no laboratory can reliably restore information that has been overwritten or securely erased. Be cautious of services that promise guaranteed recovery or request payment before examining the media.

Follow a controlled recovery checklist

Use this sequence to reduce further damage and keep the process organized:

• Disconnect the infected computer and all shared storage from networks.
• Photograph ransom notes, altered extensions, and error messages before changing anything.
• Identify the ransomware strain and check trusted sources for a legitimate decryptor.
• Preserve a disk image or hand the original drive to a qualified recovery professional.
• Restore recovered files to clean storage, scan them, and verify that they open correctly.

Once essential files are secured, reinstall or thoroughly clean the operating system before returning the computer to normal use. Change passwords from a separate trusted device, enable multifactor authentication, and review cloud accounts for suspicious activity. Keep at least one backup offline or otherwise protected from ordinary network access.

Act quickly, but avoid rushed repair attempts. Disconnecting the system, preserving the original media, and checking every safe backup source gives deleted files the strongest chance of recovery when a decryptor is unavailable.