Why has my SD Card suddenly stopped working? It is not visible on phone and I cannot format it on PC In the morning, I tried to start my Android 4.4.2 phone. There was no response from the phone for some time, which was unusual. Then it started suddenly, and I noticed that there was a notification- 'Preparing SD Card, Checking For error'. All my apps and data installed on the SD card were missing.

After some time, the notification vanished, with the problem persisting. I tried to shutdown my phone, but in the middle of the shutdown process, the phone hanged. I waited and after some minutes removed the battery and restarted. No progress. Now, whenever I shutdown the phone with the SD card on, it hangs in the middle of the process, and I have to remove the battery. Without the SD card, the phone runs fine.

I then tried backing up the data and formatting the SD card on PC. It would not get formatted, and show the message- 'Windows was unable to complete the format'. I tried formatting with quick format on and off. Also, if I manually delete the files from my SD card, they come back after a while. Though the backup version of the data that I have saved in my PC behaves normally and gets permanently deleted if I delete it.

I scanned my SD card with two antiviruses with no result. I also tried easeUS Partition Master to format the SD Card on PC, with no result. I also tried formatting via Disk management on PC.

I would like to know the cause of this random error. The card could not have been damaged because it was securely installed in my phone when this happened. Also, I downloaded some songs from a known website the last evening, and virus could have infected my phone then, although I have previously used the website with no problem.

Please explain any possible reason why this could have happened, and a solution if possible.

I also notice that when SD card is in the phone, the battery gets consumed very fast.

Also, i tried formatting it using command prompt, and got an error message-'invalid media or track 0 bad - disk unusable'.
It sounds like the SD card went bad, things like that happen.  I would recommend getting a replacement SD card.