PS Vita Slim Won't Recognize Memory Card

Attempt to hard reset the system by holding the power button for at least 30 seconds to perform a hard reset.

Make sure that the system is completely off. Next take the memory card out of the system making sure that there are no debris in the way of the golden contact pins.

Turn the system back on. There should be a message stating there is not a memory card inserted. While the system is on, put the memory back in making sure that it goes all the way in and makes a clicking noise.

If that does not work turn the system back off. Then reinsert the memory card and turn it back on.