USB wont mount, how can I recover data?

Yes — you likely can recover your files without paying for Disk Drill, and based on what you described, the data is probably still there. The “can’t be unlocked” message strongly suggests the drive is encrypted (APFS or HFS+), and macOS is failing during the unlock/mount step rather than the data being gone.

So why this is happening? From your symptoms:

• “Can’t be unlocked”
• “Internal state error”
• Disk Drill sees files
• System Info shows wrong free space

This points to: Corrupted APFS encryption metadata, not dead storage. The drive is readable at the block level — that’s why recovery tools can see files.

Before doing anything else: do not erase, reformat, or run First Aid again on that drive. Those can make recovery harder.

Here are some steps to try to gain access to your data:

• Open Terminal and run: diskutil list. Confirm the identifier is really `disk2s2`, then try: diskutil mount disk2s2.
  • If it’s encrypted, try unlocking it: diskutil apfs unlockVolume disk2s2
  • If it asks for a password and accepts it but still won’t mount, that means the filesystem is readable but the mount metadata is damaged — perfect case for recovery tools.

There are some free recovery tools that can be used to copy files:

(NOTE: If this data is critical to you, I highly recommend using either a paid version of a recovery tool or using a dedicated recovery service.)

• PhotoRec (part of TestDisk) – ugly UI, but extremely powerful and 100% free
• DMDE Free – allows limited free file recovery per session
• R-Studio Demo – lets you verify recoverability before deciding

ninjaphrodite wrote:

PhotoRec opened in Terminal, but Terminal said "No hard disk found You need to be root to use PhotoRec."

Expected behavior. IIRC, it should prompt you for your admin user password. Or you can launch PhotoRec using "sudo". You need to understand the tool you are using. Did you read the actual documentation for PhotoRec? If you had looked at the PhotoRec documentation, then you would see that the APFS file system is not listed. In fact when I tried TestDisk/PhotoRec some years ago, it did not run properly with the later versions of macOS. It can take time (lots of time) before some apps like this are even made compatible with newer systems & technology.

DMDE seems to be stuck. I let it run overnight, restarted the search with screensaver off & waited overnight again & it was still running, but never made it past 3%.

After scanning all night, R-Studio says 11.6 days remaining!

Normally when this happens it is due to a hardware issue....usually due to a failing Hard Drive. Unfortunately you have not provided us with any specific details about the hardware involved. If a drive is failing, then you should stop everything right now or you may be making the problem worse where even a professional data recovery service is unable to recovery any data. Again......is DMDE fully compatible with the version of macOS you are using and the file system with data you cannot access? Don't blindly use tools suggested online without reading their documentation to make sure they are compatible with your system & your needs.

I'm using a 2015 MacBook Pro booting from an external SSD. There's also a 2020 MacBook Air, but I don't trust it, since it couldn't even restore my backup during setup & the keys don't match the keyboard, so if there's any workaround I can use with the 2015 + external that would be great!

You have not given us any specific details here. I cannot interpret what this is saying. Stay focused on the actual drive & system with the bad drive. We don't care about any other system if you cannot trust them & providing details on them is just confusing.

• Is it the internal SSD of the MBPro 2015?
• What OS was installed on the internal SSD and what OS is being is on the external drive used to boot this laptop?
• And is that SSD the original Apple OEM SSD or is it a third party SSD using an adapter?

You seem to be ignoring the most important thing here.....providing relevant & very important details regarding this system & this drive. The contributors trying to help you here are completely in the dark here on details even after asking some specific questions & gave instructions for things to try to provide us with more information. I just asked a few more questions here.

@Tesserax mentioned some very critical points and even gave some Terminal commands to try to help you access the data which also would have provided us more detailed information on the problem. The only thing @Tesserax missed with those Terminal command was adding the " -nomount" and " -readOnly" options to those commands.

From your first post, it almost sounds like Filevault may be enabled on this drive. I've seen APFS volume corruption a number of times. Whatever you do, do not try to disable Filevault. If the FileVault status is changed, then no utility can operate on that drive including data recovery software because the APFS volume will exist in a mixed state, partially encrypted & partially unencrypted. The consumer level utilities can only handle a single file system, not a mixed file system. At that point, you need to go to a professional data recovery service to see if they can retrieve anything.

We cannot help you when we are in the dark. The results of these various data recovery apps are meaningless without details. Normally before I attempt data recovery, I will gather more information about why I cannot access the data in the first place. And to figure out if a hardware failure is involved.

You are also discovering why data recovery services are so expensive. Many times there is more to data recovery than running an app & magically getting your data. You have to understand the hardware & issues involved in the failure in order to be successful at recovering the data without making the problem worse. Many times you get only one chance at recovering the data. If data recovery was easy, then there would not be a whole industry around it.

I also hope you have learned how important it is to have frequent & regular backups of all your important data whether it is on the computer's boot drive, external media, or in the cloud. You may or may not get the data back from this problem drive.

What Mac running what macOS version are you using to recover? That might be helpful for us to know.

Thanks.

And what file system is being used on that external drive?

And what is the exact model of your Mac? You can get the exact model of your Mac & version of macOS by clicking the Apple menu and selecting "About This Mac".