Why is my memory card not being detected in any device?

[Android Central Question]

Yesterday I was running low on battery. I had a spare one so I switched it. Then the memory card stopped getting detected.
Neither it says damaged card nor anything. It says nothing at all. I tried it on other devices and same thing happened.
Plss can anyone help me .
I have important data on it.

 

[belodion]

They sometimes fail. Try cleaning the contacts.

 

[Rukbat]

If you slid it out of one device and slid into another device and it still didn't show up, I'd bet on its being defective. Just sliding it out and in wipes the contacts enough to clean them. It's just a coincidence that you changed the battery at the same time. (If it's a SanDisk, go to SanDisk microSD Tech Support. Live chat is at the upper right. They'll replace it for you unless it's really old. [The cheapest ones carry a 5 year warranty.] If it's from another vendor [only SanDisk and Samsung actually make the chips] look on their site for warranty information and, if it's still under warranty, for tech support or RMA.)