restore system to before this happened....

My mouse broke, using another one and two days ago while dragging the mouse something magical happened and my MAc began to move my entire computer or at least a huge amount of photos to my desktop. Not knowing what to do i simply closed everything and shut the computer off. I now have maybe 50 pictures on my desktop neatly stacked on top of each other and some of my original settings have been changed. What to do....Is there a restore system or go back to a previous time I can use?

Do you have a backup prior to the " magical event " ?
If so, you can use that to restore.
If no backup, you will need to " undo " everything manually.

Cheers ... McBie