Software update I accidentally erased my pictures by clicking all on format. How can I retrieve them.

You can try camera photo recovery software like asoftech photo recovery, you can refer to this tutorial
Recover Pictures from Digital Camera

Hope this helps.

Maybe, what ever you do dont take any more pictures with that card. Down load and install a program called recuva, http://www.piriform.com/recuva
Put the memory card in a usb card reader, attach that to your computer and run recuva and scan your memory card. You may have to do a deep scan to recover any files off of it.

Format completely erase the card and optimizes it for the camera's operating system. Once formatted, the pictures are gone.

There are indicators the data is corrupted on the memory card and the camera wants to format in an effort to correct the problem. If the photo's you have are important there is software available that might be able to retrieve some of your photographs. But if they are expendable then attempt the format in hopes it will correct the problem.

if you havent copied anything onto it since the format you might be able to. i have used a program called File Scavenger 3.2 and have successfully recovered files. a friend of mine gave it to me, but you might be able to find a download on one of those torrent sites

Well, no matter you photos in Canon camera got deleted, formatted by accident or became inaccessible due to camera memory card errors. Chances of recovery is possible as long as you take the right action.

Take a try of this Canon photo reocvery software, Not only general photo formats, but Canon RAW photo formats (.cr2 or .crw) can be retrieved easily.

Note: before the photos are recovered, Never should you attempt to take more photos or save more data to the memory card in case chances of photo recovery might be reduced. Hope it helps. Regards.

Possibly depending on the type of format that you did. Take no more pics until you've recovered the photos (or else you may start overwriting some of them), take the card out of the camera. Here's some freeware photo recovery software that should be what you're looking for:
http://camerarepair.blogspot.com/2007/12/recovering-those-accidentally-lost.html

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

http://www.amazon.com/s/ref=sr_st?keywords=card+reader&rs=172282&page=1&rh=n%3A172282%2Ck%3Acard+reader&sort=price

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:

http://camerarepair.blogspot.com/2007/12/recovering-those-accidentally-lost.html

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

http://www.amazon.com/s/ref=sr_st?keywords=card+reader&rs=172282&page=1&rh=n%3A172282%2Ck%3Acard+reader&sort=price

Finally AFTER you've recovered your photos, consider formatting your card IN YOUR CAMERA (did you do this when you first got the card? if not, this is what eventually happens). Keep in mind formatting the card will also totally and permanently erase the card. Press menu, then select the tools menu, then scroll down to the selection stating your cards memory capacity and select it. Then follow the on-screen prompts for a "low-level" format. This should help prevent this from happening again in the future.

The only way to retrieve after a format is to use a recovery software that does that type of thing. It does not have a recycle bin and even if it did a format removes everything. the only way to recover is using a software such as the one at www.cdroller.com You can go over the features of the software so you understand what it does.

If you have a card-reader on your computer, insert your card and all the pictures should still be there unless you have formatted your card.
Good-luck!