Accidentally deleted ~/.config directory

.config folder contains your application configurations. Whether it is system level or user level depends on the location.Yours look like user level config.

Check this post.

What have I lost? How will affect my computer?

You would likely lose any user level custom configuration/settings you may have set for any app that adheres to the XDG Directory Specification.

$XDG_CONFIG_HOME defines the base directory relative to which user specific configuration files should be stored. If $XDG_CONFIG_HOME is either not set or empty, a default equal to $HOME/.config should be used.

Most apps in this case revert to default settings. You may have to manually add these configurations again. Note: Certain applications that have their own config folder instead of using config will not be affected.

The ~/.config directory contains application configuration related to your user account only. Deleting it will return the configuration for those applications to their default value, as if you had not used them before.

Whether this is a problem for you depends on what applications you've been using and configuring.

It does not affect any system-wide configuration of any applications, only the customizations added for your user account.

You have removed all the user specific modifications or properties (for that specific user) for the applications that use directories under ~/.config to dump and read configuration. Generally, all the XDG applications use ~/.config; ~/.config is used to set or override any user specific configuration of an application set globally elsewhere.

This is not a problem per se, given you are want to set those again, or prompted to be set or happy with th globals.

At the very least, i would suggest you to run:

xdg-user-dirs-update

to create the file ~/.config/user-dirs.dirs (XDG_CONFIG_HOME defaults to ~/.config) that contains various XDG_* directory directives that many applications use.

You should get your ~/.config/user-dirs.dirs having:

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"