Lost ALL my pictures on Macbook Pro!!

Hello everyone.

I recently switched from a PC to a Macbook Pro (last week!) and synced all of the photos/videos from my iPhone to the laptop, then deleted them from the phone as it was taking too much space. The 700 something photos & videos were from a trip I took 2 weeks ago, and since my digital camera was out of memory, I took ALL of the pictures from my iPhone, & needless to say, these photos are all I have left from that trip. Now you can understand why I freaked out today, as I go into my iPhoto library and NONE of my files are there. They are NOT on any other folder, NOT on my iCloud, and of course NOT on my iPhone anymore. These files were not backed up anywhere else, because I just purchased the computer last week, and did not think I had anything to worry about for now, and boy, was I wrong. I called Apple Care and even they couldn't help me...they asked if I had done any updates, and I did, to OS X Mountain Lion on Sunday (5 days ago), but all of my files were still there until at least tuesday night (last day I checked my iPhoto library). The guy from Apple Care set up an appointment for me at the Genius bar, but it's not looking good. If anyone knows how to make these files magically appear again, please, please, let me know!

Thank You.

Is anything else missing like documents or music or videos?

You did not rename your account did you?

No, I did not rename my account.

& Yes, I lost pictures & videos, and as for the music, the only way to access from the laptop was if my iPhone was plugged in.

That so sounds like the account got changed. Try clicking on the hard drive then in Users. What do you see there?

I see my drive and the guests (sharing).

If you click on your account and on Pictures, what is in that folder? Do you see a large file called iPhoto Library?

iPhoto library is there, as well as the Photo Booth

How large is the iPhoto library? How many pics did you have? If the actual library is there it might be something in iPhoto, or iPhoto made a new blank library. What is the size of the library?

I had about 700 pictures there, now all I have is 54 pictures (not even from my phone, these were automatically taken from my email accounts).

& today when I first clicked on my iPhoto library, it immediately prompted me into creating a blank library, because according to the software, I didn't have a library at all. This is when I realized, all of my pictures & videos were gone.

As for the actual size, it says "7,451,509 bytes (7.5 MB on disk)".

& it also says it was created today.

Also, when I click on users, then pictures, it only shows the "iPhoto Library" icon & the "Photo Booth" icon. Should I be seeing the "iPhoto" icon there as well?