To get your thumb drive back, you can try using a tool like `dd` or a USB formatter to erase the drive. Since there are non-accessible partitions, you might need to use a tool like `gpart` or `parted` to delete the partitions before erasing the drive. Alternatively, you can try using a ChromeOS-specific tool like `chromeos-usb` to create a new recovery image and overwrite the existing partitions. Be careful when using these tools, as they can potentially damage your drive if not used correctly. It's also a good idea to back up any important data on the drive before attempting to erase it.
If you can't delete data or files from a USB drive using normal methods, you can try formatting it. To do this, plug the USB into a device, such as a tablet or computer, access the settings, transfer the data to the device or a backup tool, and finally reformat the USB. This will clear the storage space on the USB.
To solve this issue, there are two stages to follow. First, it's essential to back up any important data to another device, whether it's a software or another utility, to prevent any potential loss. Once that's done, the next step is to format the USB to resolve the issue.
Stage 1. Back up Important Data to Another Device
If you don't have another USB, you may download and use a backup program to do it. Qiling Disk Master is worth a try.
Stage 2. Formatting the USB on Chromebook
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For a reliable and secure backup solution, consider a combination of on-site and cloud storage. Use a reliable backup software to clone your hard drive, and store the backup on an external drive or NAS.