Micro SD Card not opening

just recently out of the blue my tablet wont open image files on my sd card.

I take photos to the internal memory and have a tidy up moving them to a file on the sd card. Hasnt been a problem. Now the tab doesnt acknowledge the files or space the occupy. Put the card into the computer all is good, remove and mount into the Tab storage space available indicates an empty card.

I have tried all manner of start up combinations with and with out the card etc and it wont pick it up ???