If you accidentally deleted one of your Ubuntu user directories (like Desktop, Music, Pictures, Templates etc), you can fix them by editing the file ~/.config/user-dirs.dirs.
# This file is written by xdg-user-dirs-update # If you want to change or add directories, just edit the line you're # interested in. All local changes will be retained on the next run # Format is XDG_xxx_DIR="$HOME/yyy", where yyy is a shell-escaped # homedir-relative path, or XDG_xxx_DIR="/yyy", where /yyy is an # absolute path. No other format is supported. # XDG_DESKTOP_DIR="$HOME/Desktop" XDG_DOWNLOAD_DIR="$HOME/Downloads" XDG_TEMPLATES_DIR="$HOME/Templates" XDG_PUBLICSHARE_DIR="$HOME/Public" XDG_DOCUMENTS_DIR="$HOME/Documents" XDG_MUSIC_DIR="$HOME/Music" XDG_PICTURES_DIR="$HOME/Pictures" XDG_VIDEOS_DIR="$HOME/Videos"
For more information about those "xdg user dirs", see http://www.freedesktop.org/wiki/Software/xdg-user-dirs.