all of a sudden my phone said the card was corrupt. I tried it in another phone and got the same message. I have no idea why. no problem with my phone or damage. Can the content be recovered? Is the card ruined? I have only had it 6 months.
thank you. Jan
13 years later, and somehow this is still relevant. 
Memory cards can fail without warning, even when they look perfectly fine. If you still have the card, don’t format it or write anything new to it. There’s a good chance the data can still be recovered, depending on whether the card is detected properly.
For now, don’t format the card or save anything new to it. Try connecting it to a computer with a card reader and see if it’s detected. If it shows as RAW or asks you to format it, stellar photo recovery software may still be able to get your photos and videos back.
It may still be recoverable, especially if the card suddenly became corrupted and you haven’t formatted or continued using it. I’d stop using the card for now and don’t choose any “format” or “repair” option, as that could make recovery harder. Try connecting it to a computer with a card reader and use data recovery software to scan it. If the card isn’t detected at all, or the scan causes errors, a professional data recovery service may be the safer option. SanDisk notes that file-system corruption or card failure can cause these symptoms.