I put my 16 gig micro SD card into a friends phone and it said it needed to be formatted. I did and after it said it doesn't read the card. I tried it in my tablet and PC and they don't read it either. It has worked in my tablet before. Is there any way to get it to work again?
Try finding the card in Disk Management (diskmgmt.msc) and assigning it a letter and path. It may require being reinitialized, which will result in all data on the card being lost.
Other than that, try putting the card in a MicroSD to SD adapter and seeing if the machine will recognize it then. I have had issues in the past with larger cards working in my otherwise functional card reader's MicroSD slot.