SD card blank or has unsupported filesystem fix
4 posts about this and i think i found a way to fix this with windows. it did this to me and worked so thought id share so people dont format the sd card and lose all data.
i put the sd card from my sensation 4g into my computers card reader. in windows 7 i went to start > rightclick "computer" and click manage. i then clicked on "Disk Management" to see what type of condition the sd card was in. it said it was a RAW disk. i started to think and then decided to try a chkdsk to see if it fixes it. to do that i just clicked START > RUN (or START > type in RUN and click the run shortcut) and type in CMD in the box then click ok. now in the command prompt type in CHKDSK X: /R then press the enter key (NOTE: X represents the drive letter). wait for it to do its thing and it should fix this problem.
i am not sure if it will fix it for all cases but atleast it worked for me.
[CARRIER] T-Mobile USA
[PHONES] Samsung Galaxy S 4 SGH-M919
HTC Sensation 4G
Samsung Sidekick 4G
Google Nexus One
BlackBerry Curve 8900
BlackBerry Pearl 8120
BlackBerry Pearl 8100
Nokia 3390 Gold
[RECOVERY] ClockworkMod 126.96.36.199