Why is my SD card not working on my Android?

In some cases, the SD card is not fully inserted into the phone, which causing the Android phone to fail to recognize the SD card. Before trying other methods, please try to remove the SD card from the phone and then reinsert it. The first thing is to turn off your Android phone and remove the card out from your phone.

Is it possible to clean an SD card?

It is just like how you clean simcard.