How do you get all your pictures back when you accedently erased all of them

Firstly, stop using this camera immediately in case that any new file would overwrite your original photos and make them gone permanently. So, you should take care!
Secondly, plunge this camera to your computer and prepare to retrieve all your deleted pictures.
Thirdly, apply a deleted photo recovery freeware to retrieve all your deleted photos back successfully:
http://blog4mark.blogspot.com/2012/12/photo-recovery-after-delete.html
I believe this data recovery freeware can work perfectly on your camera memory card just in the same way as it completely retrieves all the deleted data of my friend off from his phone memory card. Just give it a shot!
Fourthly, save and back up all the restored photos on a different camera memory card or drive in case of data recovery failure.
Note: Never forget to back up everything important at least on two memory cards or locations in the future.
Good luck!

If you are using a memory card, take no more pics until you've recovered the photos, take the card out of the camera. This is to reduce the chance of you overwriting some of your "lost" photos. There are many good freeware photo recovery software options that are available to help you recover your photos. This blog article reviews and outlines several of the better ones.