My 9-month-old Transcend 32 GB micro SDHC card has gone tits up.
One day, Android just flashed up in the corner: "SD card is blank or has unsupported filesystem."
I have a micro SD-to-USB converter and when I plug that into my PC and double-click on the drive, Windows tells me no disk is inserted.
If I insert the micro SD card into a micro SD-to-SD card converter and that converter into a laptop's card reader, Windows asks me to reformat the drive. If I choose OK, the top box ("Capacity") shows 30.6 MB, so I haven't formatted it yet.