alcatel idol 3 - sd card problem

[AC Question]

I fitted a 64gb sd card in my idol 3 and it worked fine, I transferred stuff across and now it doesnt work anymore. I cant access stuff on sd card, it is not recognised by the phone and if I press the "mount sd card" , nothing happens, it just flashes back.

I dont know what I have done and have no idea how to fix it, the phone does not appear to recognise that the sd card is there, HELP!!!!

thanks