how can i repair my micro sd card when it don't show to any device?

[Deep Mandal]

I put my 4gb class 4 micro sd card in my wallet for few days during my smartphone went to service centre for servicing...when I get back my phone..again put the card on the phone but my phone can't read it...then I put it to a adaptor & insert it to my laptop...but my lapy also failed to read it...although it seems looks like normal & not broken through any side...plz help me...

 

[Reynod]

Try cleaning the contacts with a cotton bud and some alcohol wipes ... failing that get a new one.

Putting it in the adaptor on a laptop or other device and trying to reformat it first.