I took the photos but unable to see in the camera but the memory card is occupied with the photos i took...so how can i retrieve the photos ? kindly help me :)

Is it virus-infected?
In my personal experiences, your problem could be resolve in these three ways:
1). Try to unhide these files.
According to your description, your files may be hidden anyway. Try to show them all up again:
Start => Run => Type in "control folders" and press "OK" =>Click "View" and hook "Show hidden files and folders"=> Press "OK".
2). Scan your camcorder with antivirus tool
Sometimes, the virus also would hide the files make them invisible for you. So, just try to do antivirus scan on your computer. (You should take care not to delete some needed files in the process.)
3). Restore your files back by using a deleted photo recovery freeware:
http://blog4mark.blogspot.com/2012/12/photo-recovery-after-delete.html
This problem also could be caused by the camera problems. So, if you want to save these files, you'd better try to use a photo recovery freeware that always could help retrieve the inaccessible files back for free:
http://www.freeware-fix.blogspot.com/2013/02/photo-recovery.html

Take no more pics until you've recovered the photos, take the card out of the camera. Here's some freeware photo recovery software that should be what you're looking for.

You will need to use a flash card reader with this software. If you don't have one, get one, they're inexpensive.

The reason this occurred is that you likely never formatted the card. The card will work fine in the beginning but eventually will corrupt.

AFTER you've recovered the photos, format the card in your camera to prevent this from happening again. Go to the "tools" menu, and select the item stating your memory card's capacity. Then follow the on-screen prompts. But keep in mind formatting will also totally erase your card, so again only do this after you've recovered the photos.