Linny try this : insert the card into usb via adapter,
go to "run" and type in Cmd" - this will bring up a little black screen.
in here it should read "C:\windows\system32>
where the blinking cursor is type in "chkdsk E:/r" and hit enter
this will re-start the card through dos, let this run for a while and it should find any problems and try and re-build any bad sectors of files, when it is finished you should be able to access of re-format then
give me a shout if this helps or not :)