sd card not opening.but i have installed .so what should i do?

[AC Question]

Not opening sd card.showing not installed sd card..but i have cheked many time that installed perfectly..i thought it's a software problem .thatswhyi have to discuss with you

 

[B. Diddy]

Welcome to Android Central! Which phone? What brand of SD card is it, and where did you get it from? The card may be defective or counterfeit (the latter being more common if you bought it online from some random seller for really cheap). Remove the card from the phone and insert it into your computer's SD reader. If the computer can't read it either, then it's a dead card. Get another one, and make sure you get it from a well-established online store (like Amazon, not eBay) or from a reputable local store.