I dont see any files in my camera sd card

Hello,
I recorded some important videos in my panasonic digital camera in its sd card.
It worked in the camera.
I just removed the sd card and put in a card holder and inserted it in my windows 7 pc.
i opened the drive.
there was a link file named sd card 4 gb.
i opened the link
i found all my photos which i captured before, but not the video.
i took some photos also that day but i dint find that also.
after that, i put the sd card back in my camera.
it said there is no valid pictures to play.
what do i do
is there any way to recover my photos and videos?