I accidentally lost the data in cam. mem. when i was trying to transfer info to sd card now both the cam mem and images prev on card is gone. is there any way to retrieve..... pls. help

You can use some camera recovery software to get back pictures erased from camera. You can refer to this tutorial that helped me before
Recover pictures from camera

You can view this camera video recovery tutorial that helped me before

Try Card Data Recovery. it can recover data from memory card, memory stick, SD card, CF card, etc.

Do not take any more pictures, and remove the card from the camera to lessen the chance of you overwriting some important pictures or videos. There are very many freeware software options available to help you recover your files. Please see this article that reviews several of the better freeware recovery programs that you can try (and yes, these truly are freeware). You may need to use a card reader with these programs though.

Put your card in your computer if you have a card reader, or use your cable from the camera.

Domnload RECUVA software it easy and works well to recover lost pictures. Install it and choose the drive you want to recover, in this case your camera memory labeled as removable device.
As long as you didn't use the card after loosing the pictures you should be able to recover all of it.

Hope this helps