A few years ago, I took a series of approximately 1500 shots of our area, while my wife was on a nursing assignment. I PSed many of them and posted them on a website for friends to view. While working with the shots, I neglected to save all the originals in the order in which they were taken. I would now like to recategorize them so that they're in chronological order. They were all taken with the same camera over a period of close to four months. I did not use the option of date/time so that I wouldn't have that stamped on the pics. If it's possible to recover their order, how do I go about it? I have PS, and usually use irfanview for simple viewing. Thanks for any help.