hi guys..this is the thing..i hope someone could help me

I got a D-390 camera, and it was working really good, when suddenly it started to give me some trouble

example: i open the lens barrier and take....10 pictures....after that,,,i can see them all, in the monitor, but after that, I close the lens barrier....and when I try to visualize the pictures AGAIN, it does not show anything, and it says that there's no picture....but when i connect my camera to the computer,,,the pictures are there....weird...isn't it??

am sick and tired of this....i hope u guys can help me....thanks a lot