I'd be curious to know what kind of card this is (brand, etc). Assuming it's an offbrand, you should consider investing in something like a Sandisk or PNY SD card. Keep in mind that with these cards you are getting what you pay for. Far better to pony-up the extra $20-$40 for a card that won't crap out on you and lose all your data.
Jamroom brings up a great point that a cardreader is also a very valuable investment. You can pick one up for dirt cheap in any Best Buy. Aside from allowing you to remove the hurdle of reading your data through a device (a process which can be cumbersome when working with certain devices), an external card reader will also allow you to pop out your card from your device read it without sucking up battery life. These cardreaders are really handy and worth their weight in gold.
That having been said, if you are trying to recover that data which is unreachable from your SD card, I have had good success with a freeware restoration program (available
here). This program will let you select a drive (your card should be being recognised as a drive) and search through deleted and corrupted files. Sometimes Windows gets tempermental about transfering even slightly corrupted data. I had this happen with a show once and upon recovering the "untransferable" file with this Restoration utility, I was able to listen to it just fine, track it out, EQ it, .flac it, and share it without any problems whatsoever.
SO: In recap, get a new SD card and pay for a good one-- get a card reader-- and get this restoration utility.
Best of luck