why is my sd card not working in my phone

[dwaynem320]

My sd card was working perfect until a few days ago, now my phone (galaxy s4) keeps sending me a notification saying my "sd card unmounted" when clearly it isnt! Could this be because my memory card is full??

 

[accessgamer]

Switch off the phone, Remove Battery, Remove SD card , Remove SIM Card and replace them all back and restart the phone and see if this helps.

 

[sumitshivam132001]

Switch off the phone, Remove Battery, Remove SD card , Remove SIM Card and replace them all back and restart the phone and see if this helps.

I did this but not working again._!!!!!