iphotos won't open
I was in the process of deleting unopenable files from an external harddrive, to clean it up to have it reformatted for my Macbook Pro (it had previously been used with a PC). I deleted or saved everything needed except for pictures. I had previously uploaded pictures from this ehd onto my Mac, but was going to go through the folders to make sure they were all there before deleting them from the ehd. When I wen't to open iphotos, it will no longer open. The white wheel in the center of the screen just keeps spinning. What happened? I was not deleting anything from my mac, just the ehd, but iphotos is now acting as if I deleted something crucial to let me open it. I do not notice anything else acting up on my Mac.
HELP!!!!
iPhoto '11, Mac OS X (10.6.8)