I deleted by mistake a wallpaper to trash. I cut it out of trash and paste in to my "Pictures" folder. But now when I go to the pictures folder, the picture is nowhere. Its not even hidden. What can I do? Please assist.
Well if you have a rough idea of the filename you can search your entire computer for it.
sudo find / -iname 'butterfly*.jpg'
Or if that's prohibitively exhaustive, you can do a more limited (but quicker) search of just your home:
find ~/ -iname 'butterfly*.jpg'