USB flash drives -- also called keychain drives -- have replaced floppy disks as the portable storage medium of choice for many people. However, these small drives can be damaged fairly easily if they're bent or twisted while they're plugged into a computer. Such damage
can destroy the data outright, or simply make the drive inaccessible.
The latter is typically manifested by the computer entirely failing
to recognize the drive when it's plugged in.
Data can also become corrupted due to driver or other software problems. In those cases disk recovery programs like Norton or BadCopy Pro may be able to restore or recover data from the device.
The SanDisk company offers
as well as an unadvertised data recovery service. SanDisk drive owners should contact their support and then send SanDisk proof of purchase before they will issue an Return Materials Authorizations. Other drive manufacturers may offer similar services.
In the case of physically broken drives, technically-savvy owners may have luck manually opening the drive casing and looking for broken connectors or cracked solder joints. Some people have been able to manually reconnect broken connectors long enough to get the data off the flash drives onto a computer. This of course will void any warranty.