Important Data Lost? What to Do and What Not to Do?
What to Check First — and How to Avoid Making Data Recovery More Difficult
Have important files disappeared from your computer, external hard drive, USB drive or memory card?
Data loss does not always mean that your files are permanently gone. The situation can range from accidentally deleted files to a failing drive, damaged hardware, corrupted partitions or a serious file-system problem.
What you do immediately after data loss can be important. Continuing to use the affected storage device, formatting it or installing software onto it may overwrite information that could otherwise be recoverable.
In this guide, we explain what to do first, what to avoid, and when professional data recovery may be appropriate.
What Does "Data Loss" Actually Mean?
Files were accidentally deleted
No lights, fans or sounds, power button appears to do nothing?
May indicate a power supply, battery, charger, motherboard or other hardware problem
The drive is detected but files are missing
Fans or lights may be working, but nothing display
Possible display connection, monitor, RAM, graphics or motherboard issue
The drive is not detected
The operating system is starting but get stuck in initialize
Common causes include system files corruption, failed updates, drivers or storage problems
The drive makes unusual noises
Starts, shuts down and starts again
May indicate a Windows/macOS problem, hardware fault, overheating or failed storage
The computer says the drive needs to be formatted
Windows detects a serious error during startup
The cause could be hardware, drivers, system files or a recent software change
Files became inaccessible after a crash or power failure
Mac is trying to boot but stuck there with a flashing question-mark folder
This generally means the Mac cannot find a usable startup disk or operating system.
The drive was dropped, damaged or exposed to liquid
The computer cannot find a drive containing a bootable operating system
The SSD/HDD, boot configuration or Windows installation may need attention
Common Causes of Data Loss
- Accidental deletion — Files or folders may have been deleted by mistake.
- Formatting — A drive or partition may have been formatted before important files were copied elsewhere.
- Failing HDD or SSD — Storage hardware can develop faults that make files inaccessible.
- File-system or partition corruption — A damaged file system or partition table can make a drive appear empty or unreadable.
- Physical damage — Drops, liquid damage, electrical faults or damaged circuit boards can affect storage devices.
- Power failure or improper disconnection — Unexpected shutdowns or removing removable storage while it is being written can cause corruption.
- Malware or ransomware — Malicious software can delete, encrypt or otherwise make files inaccessible.
- Overwritten data — New data written to the affected storage area can reduce the chance of recovering deleted files.
What to Do When Important Data Is Lost?
On Windows
Including Windows7, Windows10, Windows11 and so on, whether running on a Desktop PC, Laptop, All-in-one Computer or Tablet.
On Windows — protect the affected drive first:
1. Stop unnecessary use- Stop saving new files to the affected drive.
- Do not install recovery software onto the same drive containing the lost data.
- If the drive is making unusual noises or repeatedly disconnecting, stop using it.
- Check the Recycle Bin if files were recently deleted.
- Check whether the files are available in a known backup or cloud-sync location.
- Check whether the drive and its partitions are still detected in Disk Management.
- Do not format the drive simply because Windows asks you to.
- Do not repeatedly run repair or recovery operations on a physically failing drive without considering the data first.
- If the data is important and the drive is failing, damaged or not detected, stop and have the situation assessed before further testing.
On a Mac
Including macOS versions such as Ventura, Sonoma, Sequoia and Tahoe, whether running on a MacBook, iMac, Mac mini, Mac Studio or other Mac computer.
On a Mac — protect the affected drive first:
1. Stop unnecessary use- Stop copying or downloading new files to the affected storage device.
- If the drive is making unusual noises or repeatedly disconnecting, stop using it.
- Do not install recovery software onto the same storage device containing the lost data.
- Check the Trash if files were recently deleted.
- Check Time Machine or another known backup if one exists.
- Use Disk Utility only to check whether the storage device is detected; avoid erasing it if the data is important.
- Do not erase or reformat the drive just because macOS reports a problem.
- If the storage device has physical symptoms, avoid repeated attempts to access it.
- If the data is important and the drive is failing, damaged or not detected, stop and have the situation assessed before further testing.
When Should You Stop Troubleshooting?
- The hard drive or SSD is not detected.
- The hard drive is clicking, grinding or making other unusual noises.
- The drive repeatedly disconnects or becomes extremely slow.
- The computer reports that the drive needs to be formatted.
- Important business, family or irreplaceable files are involved.
- The storage device has suffered a drop, liquid spill, electrical event or other physical damage.
- You are unsure whether a repair action will overwrite or erase the data.
- You have already tried recovery or repair software without success.
Common questions
Can deleted files be recovered?
What should I do first after losing important data?
Should I format a drive if Windows says it needs to be formatted?
Can I run CHKDSK or Disk Utility First Aid on a failing drive?
What if my hard drive is making clicking noises?
Can you recover data from a damaged or undetected hard drive?
Don’t Make Data Loss Worse
When important data disappears, it is tempting to try every repair or recovery option immediately. That can sometimes make the situation worse.
Do not format the drive, reinstall an operating system, copy large amounts of new data onto the affected drive, or repeatedly operate a drive that is making unusual noises when the files are important.
For deleted files, continued use can overwrite the storage space that may contain the deleted data. For a physically failing drive, repeated operation can also make an existing hardware problem worse.
If the files are important, stop and get the storage device assessed before taking actions that could change the original data.