iPhoto Library delete all photos- Time Machine back up cannot find photos either

iPhoto Library - all photos gone. Please help :)
Hi everyone. Please be gentle as I am not an expert but I need your help.

I have a macbook mac os x 10.5.8- it has about 3 years old.

I use iPhoto where I store all my picts. iPhoto '09, version 8.1.2 (424)

On August 10th, I did the last back up on time machine. (external driver)

On August 15th, all the pictures from iPhoto are gone. I did not erase them. Look into Mac, iphoto library, libraries, documents, etc. but I could not find anything.

I opened the August 10th back up on Time Machine. I clicked iPhoto, and open time machine. It does not open the Time Machine iPhoto back up done on August 10th nor the previous ones. It gets freeze.

I look into iphoto library- nothing in there (neither in my mac nor in the Time Machine Back up)

The only back ups I have it is one I have done manually and have the pictures until February 2011. After that is when I started using Time Machine.

Genious rep at apple store looked at it, but he could not find the pictures either, he suggested to do a data recovery (which is VERY expensive) in order to recover the pictures. He said the pictures are there.

There is nothing on Trash (iPhoto or Mac's trash)

Can you please help me? I am not sure what to do.

Thank you!
Sil