SD Card stopped working

I purchased a 9900 from AT&T about two weeks ago and it has been great until just today. I have a 16GB SD card that I have been using for some time and it worked flawlessly in my 9800 and the 9900 until today. The card was getting full so I plugged the phone into my computer so that I could clean off some files faster, deleted some files, and now the phone does not read the card. I never removed the card during this process; I only deleted photos and videos. I then loaded some new videos onto it and those all showed up fine (and play) from Windows Explorer. However, when I try to view the files from my phone, they do not show up. When I try to take a video and force it to save to the card, it shows the card as full. I have tried taking a picture and then view the photo, but it is not there. I have tried pulling the battery, pulling the battery and removing the card and then putting it all back in but nothing seems to help. I have also tried a battery pull without the card, put the card back in with a battery pull and still nothing. Under Options, Device, Storage, it shows the card in its previous, un-cleaned state. That is, it shows it as having only 1GB free when in fact it now has about 8GB free. Any thoughts?

Thanks in advance.

Kurt

Copy everything from the card to a computer. Then format the card. And then copy the data back to the card.

Well, after I let the phone sit for a while, it read the card and I was able to see the files on it. However, even though my computer indicates the card is 50% full (8 of 16GB), my phone still thinks it is full and will not let me take pictures or video. Further, I put in a different card (4GB) and the phone read it fine and indcated lots of free space. Perhaps there is something wrong with the card. I will continue to trouble shoot and post my results here but let me know if anyone else has more suggestions.

BTW: I have not tried formatting the card yet but will.

Thanks.

Kurt

I agree with SwitchBeach. My new 16GB card was acting wonky, so I removed it from the BB and put it into an adapter, plugged into my computer and did a slow format of the thing (uncheck the "Quick Format" option in Windows).

It's worked like a charm ever since.