USB Pen Drive Crisis

[Gareth Russell]

My USB Pen drive, has given up the ghost or so it appears. I get the
following error when i try to mount it

mount: /dev/sda1 is not a valid block device
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It appears that a block on the device has become corrupted and this is
preventing me from mounting it.

Does anyone know anyway, in which I can rescue this device? By finding
the bad blocks on it and repairing them?

Cheers,

Gareth