It sounds like the file system on your USB drive might be corrupted or the file may have been accidentally converted into a Unix executable.
Here are some things you can try:
- Check if the file is still visible on your Mac. If it is, try to right-click on it and select "Get Info" to see if you can change the file type back to its original format.
- Try to recover the files from a backup if you have one.
- If the file is not visible or recoverable, try using a file recovery software program to recover your lost files.
- If you suspect the file may have been converted into a Unix executable, you can try using Terminal to convert it back to its original format. Open Terminal and navigate to the directory where the file is located. Then, enter the following command: "chmod +x filename" (without the quotes), where "filename" is the name of the file. This command will remove the executable permission from the file, allowing you to open it.
- If none of the above solutions work, you may need to seek the assistance of a data recovery specialist to recover your lost files.
It's always a good practice to back up your important files regularly to prevent data loss in case of any unforeseen circumstances.
