Do you mean the SIM, as opposed to the SD card? Sorry to ask, but I've seen people confuse them.
If so I guess you can't see contacts on it. Check the settings of the contacts app to make sure it is set to show SIM contacts.
If it's the SD, can you see its content on a computer (using a card reader), or is it really wiped? If so, you could try some file recovery software (e.g. Recuva if you use Windows, which is free) and see whether you can save the data. MicroSD cards are not always reliable, though it's very hard to say what might cause an individual card to fail.