‘The disk you inserted was not readable by this computer’

You can try using a data recovery app such as Stellar Data Recovery to see if you can retrieve those photos. I've never used this app personally, but have seen numerous people on this forum mention it was able to recover their data and it seems to get good reviews.

FYI, you should always have a backup of any media that contains important & unique data. This includes your main boot drive, external drives, and even items stored or synced in the cloud. And as has already been pointed out, USB sticks are notoriously unreliable. They are at best used for transferring files between two computers or for bootable installers.

Erasing and/or formatting the usb stick will definitely wipe out whatever is currently on it. Don't do that.

But if you've clicked "Initialize" a couple of times, sadly you may have done just that. To initialize a drive is to reformat it.

It's disappointing that you don't have the photos on that flash drive backed up on another drive somewhere. Flash drives are notorious for this sort of thing.

You might try reading the drive with another Mac if you have access to one.

If you can successfully read it with another Mac, then the very first thing you'll want to do is copy the contents to another drive before you lose it for good.

mxisaki wrote:

...if it really did become ‘initialised’ wouldn’t there have been some process bar showing some initialising progress ? Oh yea also why would initialising be an option though anyways ?

Yes, there should have been several options presented to you.

Initialization is offered as a means of preparing a brand new drive for use - one with no detectable formatting or directory structure.

So this usb stick was also usable on your Windows PC? That suggests it was likely formatted as FAT with a Master Boot Record - not the preferred format for Macs, but usable. Unfortunately, it doesn't make recovery any easier.

There is apparently and obviously some amount of directory corruption going here since neither your PC nor your Mac can read that usb stick.

Sadly, if Disk Utility's First Aid routines can't resolve this I don't know what more you can do to revive that flash drive and I fear you've lost your photos. 😔

Initializing or reformatting the stick may allow you to continue using it but at the cost of any data that is/was on it. If you do that and can get the computers to mount it again, I wouldn't trust that stick any longer for data storage. I'd only use it maybe to quickly transfer unimportant files from one pc to another.

Going forward, I strongly recommend that you start backing up any other data you would like to not lose.

Use Time Machine to back up - Apple Support

mxisaki wrote:

What’s about the directory corruption ur talking about 👀?

The reason your computers cannot read the usb stick is because the data stored on the stick that identifies how it is formatted or tells where the files and folders are located - the file storage directories - have become damaged, corrupted. It happens all the time. This is why data backups are so very important.

There are apps that can be used to try to fix this damage; Disk Utility has its First Aid routines. Another app called Disk Warrior from Alsoft is one that sometimes gets recommended in the forums. But these aren't guaranteed to fix problems like this, especially with years-old drives. And flash drives are notorious for sudden failure.

Well, I see this on Alsoft's page:

❝Windows formatted drives are not supported including: NTFS / EXFAT / FAT32 / FAT16❞

so I guess DW is off the table in this case anyway.

I don't know others drive utilities to recommend. Kinda got fingers crossed here that another user can provide some additional guidance. 🤞🏽