1. Format the card (you may even need to repartition it). 2. Perform a factory reset on the android device, likely it corrupted the file system and NOT the card itself. Flash memory lasts for decades alone.
I'll suggest (in the source) to use a live linux usb or dvd (there's instructions to make one on the website), to repartition it, so you can use it again, only if windows won't allow formatting (which it should). Could also format it in a digital camera or camcorder.
If the card still doesn't work regardless what you tried, and exhausted all methods, being it to your local electronics recycling agency, don't throw it out like others suggested. Electronics never decompose, and if they do, it takes millions of years, not months.