Correcting an sd-card?

[Linux for blind general discussion]

Hi All: Some of you may enjoy types of BookPort recorders, which like others 
record on an sd-card. I use mine for recording news-programming from many 
Networks. So on the card, there are around 19 catagories alphabeticly arranged 
by channel. Beginning last week I would hear an error when hitting an item 
which it cannot access, something like minus 2thousand1hundred7. At first items 
would still play in my Linux machine, but now more items are not playing. So, 
most folks on the BookPort list are not familliar with Linux, but say I would 
un-mount the drive-and-run some sort of fix disk. Well, in looking it up, Linux 
supposedly has "fsck" but an only item I can find in aptitude is "fsck-backend" 
So, once again I loaded the card through an adapter, says,
/dev/sdg1                      250G   30G  220G  12% /media/usb0
So, can some1 please inform of the best way I can fix this card? This is Debian 
SID. Thanks so much in advance
Chime