Lost of Pictures

I have downloaded the pictures to the PC by a card reader and have not yet
saved them.

I saw the pictures 1 by1 and suddenly there was no reaction from my PC and
hanged

I restarted the PC and downloaded the picture again but failed.

I inserted the menory card in the camera and it said "No Picture"

Since this is my first time to perform this and wish to know where all my
pictures have gone and is there any way to get them back.

Pls advise by step.