why do some of my pictures are erased from my folders, and why can´t i see or recuperate photos from the garaje bin?

I

have the original pictures in jpg forma in folders, on my mac pro and then imported them into iphoto. I also have a backup on en external drive, but some of the pictures in my iphoto folders get delete just as i am browsing through them...

An apology. I have my Iphoto library just in my macbook pro. Inside Iphoto. I have the original folders on my desktop.

Greetings. Allow me to expand, please. I downloaded pictures from internet, as a collection with different themes directly from Internet. I only downloaded jpeg files or images. I organized my themes by folders on my desktop, then I copied some of them in a small 250gb external hard drive… But that´s just incidental. Whenever i had a folder of images that I wanted to play as a presentation, I just dragged the folder to the Iphoto main page and Iphoto just copies them and makes a file under the same name as the original folder. Of course I also have images of my own production, which are my main concern. But threee or four times, Iphoto said that I had inconsistencies in my pictures and I just had to agree to fix them. This operation could take up to a couple of hours por more...

But since I installed Yosemite, this glitch or question of inconsistencies, has not happened again, but somtimes, as I scroll through the folders in Iphoto, to edit some of the images or delete them, some of them become just a dotline square… I cannot see the image anymore, and when I do a presentation of the folders, these blaced out images appear in the show, as a black square or screen. I hope this information helps to answer your questions… Thank you for helping me.