I have a problem sometimes the display just comes up (SD card missing) although one is inside as soon as you take a photo, 2 minutes later it works again.
The behaviour of your Hoppstar Rookie camera (item no. 76890) most likely indicates a contact or compatibility problem with the microSD card, not a defect in the camera itself. If the problem continues to occur even with a new, correctly formatted 32 GB card, the card reader is probably slightly loose.