Programs
A quick way of backing up a list of programs is to run this:
dpkg --get-selections > ~/Package.list
sudo cp -R /etc/apt/sources.list* ~/
sudo apt-key exportall > ~/Repo.keys
It will back them up in a format that dpkg can read* for after your reinstall, like this:
sudo apt-key add ~/Repo.keys
sudo cp -R ~/sources.list* /etc/apt/
sudo apt-get update
sudo apt-get install dselect
sudo dselect update
sudo dpkg --set-selections < ~/Package.list
sudo apt-get dselect-upgrade -y
* You may have to update dpkg's list of available packages or it will just ignore your selections (see this debian bug for more info). You should do this before sudo dpkg --set-selections < ~/Package.list, like this:
apt-cache dumpavail > ~/temp_avail
sudo dpkg --merge-avail ~/temp_avail
rm ~/temp_avail
Settings and Personal Data
Before you reinstall, you should probably back up the settings from some of your programs, this can easily be done by grabbing folders from /etc and all the content from your user directory (not just the stuff you can see in nautilus!):
rsync --progress /home/`whoami` /path/to/user/profile/backup/here
After you reinstall, you can restore it with:
rsync --progress /path/to/user/profile/backup/here /home/`whoami`
So all together as a pseudo-bash script.
This assumes there is only one user on the machine (remove /'whoami' otherwise) and that you used the same username on both installs (modify dest. of rsync otherwise).
dpkg --get-selections > ~/Package.list
sudo cp -R /etc/apt/sources.list* ~/
sudo apt-key exportall > ~/Repo.keys
rsync --progress /home/`whoami` /path/to/user/profile/backup/here
## Reinstall now
rsync --progress /path/to/user/profile/backup/here /home/`whoami`
sudo apt-key add ~/Repo.keys
sudo cp -R ~/sources.list* /etc/apt/
sudo apt-get update
sudo apt-get install dselect
sudo dpkg --set-selections < ~/Package.list
sudo dselect
Disclaimer: I tried this on my ubuntu 17.04 but don't know if this works on 15.10. (I don't even know whether 15.10 uses dconf or gconf.)
In ubuntu 17.04, you can do this with dconf.
Most simply, just run gsettings reset-recursively org.gnome.nautilus in a terminal and every nautilus setting will be reset to default. If you want to reset only specific settings, gsettings list-recursively org.gnome.nautilus will give you a list of key-value pairs you can gsetting set or gsetting reset.
Alternatively, if you prefer a GUI editor, install dconf-tools package, run dconf-editor and navigate to /org/gnome/nautilus. Find the relevant keys and right click to reset/customize.
Best Answer
Open a terminal and try this command:
and relogin. In a perfect world, this would restore a stock environment without any data loss. The world is good enough that it may work for you. However, not all software is standards compliant, so... if your login is still borked, backup everything and run:
This will delete configuration for all applications. It will also delete some user information, such as your browser login information, your email credentials, save game files, etc.