Lost pictures I went to the functions menu without knowing that it would erase my precious vacation memories- I lost 263 of them and don't know how to possibly retrieve them. HELP!

Assuming you didn't download the pictures to your computer ... and as part of the download option, you elected to erase/remove the pictures (after downloading them) from the camera ... and you have not done anything (on the camera menu) to "refresh" or erase the pictures, or reformat the storage media (memory card) ...
then ...
... if the pictures are stored in a memory card .... you can take that memory card out of the camera, insert it into your computer ( ... or use a card reader, inserted into a USB port) ... and see if you can recover the "deleted" data from the memory card ...

... if the camera only has "internal" memory ... connect the camera to your computer ... and when it shows up as a storage media, try to recover the "deleted" data from the memory card ...

You can (find on the Internet) and install and use various (free) software (on your computer) to recover "deleted" files on storage media (memory card, etc.), ... on a Windows PC ... like PhotoRec, PC Inspector File Recovery, Undelete Plus (or Undelete 360), Glary Undelete, Wise Data Recovery, Recuva Free.

The best way to completely erase the card is to go into the menu of the camera and find "format" (it might be called "initialize" on some cameras) and follow the on-screen instructions.

I know how it can be frustrating not to loose your files..............my recommendation may be a bit hard but it is tried and tested.

1. Have your camera format it that is if you believe that the card is not faulty.
2. Use the card any how you want!
   
3. Get a recovery software which will recover all files that was deleted no matter what you did to the card and use it to recover all your old pictures . (i can provide this software for free if you so wish)

good luck and let me know the outcome

Are your pics on the internal memory or the memory card? With no card in the camera, can you bring up the internal memory? If not, then any pics on it are gone. Your best bet at this point would be to format the internal memory to completely erase anything on it and vow never to use it. Is there anything on the memory card? You may have to use a card reader to find out.
Had you done your homework on this camera before buying it, you would have found out that nobody likes it. It's cheap and totally unreliable. Takes horrible pics and doesn't even have an optical zoom....only a terrible digital zoom. Saving the once in a lifetime pics from a vacation requires a much better camera.

The likely reason this keeps happening is that these cards weren't formatted in the camera when you first got them. However, don't do so just yet as formatting also erases the card. 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. Now AFTER you've recovered the photos, format the cards IN THE CAMERA USING THE CAMERAS FORMAT FEATURE. Look for it, it's located under the "tools" menu (look for the item stating the card's memory capacity). This should rejuvenate both cards, and prevent reoccurrence.

You can find out how to do this on page 76 of the users manual. PLEASE CLICK HERE for the manual

Here are the instructions if you cannot get to the manual..

You can copy (backup) all the image data stored in the internal memory to the card. The image data in the internal memory is not erased by copying it to the card.
The optional card is required to use the backup function. Operate the camera with the card inserted. Top menu [MODE MENU] [CARD] [BACKUP]
• In : Top menu [SETUP] [BACKUP]
1 Select [YES], and press Z.
• All image data stored in the internal
memory is copied to the card.

GOOD LUCK!

All pictures in the internal memory and/or on the memory card can be erased at once. This is accomplished through either formatting or the "all-frame erase" function. I copied the following instructions from the advanced manual, which can be downloaded here: http://www.olympusamerica.com/files/d545zadvman.pdf. Adobe reader should open that file with no problem. If it doesn't, that's another issue altogether.

1. Enter playback mode by pressing the play button.
2. Press the OK MENU button.
3. Press the right arrow button (next to the lightning bolt) to access [MODE MENU]
4. Then, press the down arrow to access the [MEMORY(CARD)] tab.
5. Select the [ALL ERASE] function.
6. Select Yes and press OK MENU.

(You'll need to use the arrow buttons to navigate the menus. Please see pg 16 of the manual for instructions on how to do so.)

Note: when the memory card is in the camera, it will erase the pictures off the card. When the card is removed, the function above will erase the internal memory.

I'm sorry to say that the card is erased. A format is a complete erase of the memory card. 
However, your pictures aren't necessarily lost. First of all, make sure you don't use the memory card in the camera. As long as you haven't taken any new pictures on the card, you should be able to recover your pictures.
Next, you will need a USB memory card reader that accepts your type of memory card.
Connect the card reader to the PC, then insert the memory card in the memory card reader. Then download this program: http://www.datarescue.com/photorescue/download.htm
This is a program for recovering lost pictures from formatted memory cards. It's a free trial version, that will show you the photos that can be recovered. To do the actual recovery, you will have to buy the program for $29.
I hope this helps you! Let me know if I can provide more help.
Regards,
/Chris

i know its not ideal but why dont you borrow a friends camera and usb lead, put your card into their camera and upload them onto your computer via their camera, at least then you can save your special pictures and rectify the problem later

1) move left hand toggle switch all the way to left, where the little playback sign is, where it lets u look at the pics you have.

2) Press menu button once - you should see a red box with erase at the top. use your zoom toggle switch to to select "all frames"

3) Use the menu button to select ok

Card should be erased.