|Thank you for feedback; always useful to know which utility you found effective. Helps us to advise others n the future.|
I suggest that you copy anything that's on a flash/pen drive etc, to DVD - at least.
Usb flash/pen or whatever drives are not safe items for long term storage. They have a limited (albeit quite long) life time and number of writes/rewrites etc; but they will fail at some time or other; and often just when you don't want them to... ("Very" easy for them to fail at any time.)
Also easy to remove them incorrectly - without properly "ejecting them"; and also subject to data loss in event of a power failure whilst still connected and "active". And as you have already discovered - easy to erase them unintentionally!
They are really intended for easy transportation/sharing of data on the move; which data is safely copied elsewhere to DVD and/or another hard drive.