I installed Ubuntu 15.10 and after few days I installed Katoolin and now it shows Kali GNU/Linux Desktop and my Ubuntu Software Center is not working even after removing Katoolin. So how to get back to Ubuntu 15.10 without having a fresh installation?
I had the same problem after installing Kali via Katoolin on Ubuntu 16.04 and it took me some time to figure out a solution. In my case Katoolin changed the settings in the lsb_release file.
I could fix it with running:
sudo -i gedit /etc/lsb-release
There I had to change the Kali settings, which do not belong there to:
DISTRIB_ID=Ubuntu DISTRIB_RELEASE=16.04 DISTRIB_CODENAME=xenial DISTRIB_DESCRIPTION="Ubuntu Xenial Xerus"
In case you have another distro you need to adapt the names (see Wikipedia e.g.).
In your case:
DISTRIB_ID=Ubuntu DISTRIB_RELEASE=15.10 DISTRIB_CODENAME=wily DISTRIB_DESCRIPTION="Ubuntu Wily Werewolf"
DISTRIB_ID=Ubuntu DISTRIB_RELEASE=17.04 DISTRIB_CODENAME=zesty DISTRIB_DESCRIPTION="Ubuntu 17.04"
Then, run the following command to update grub:
After doing this everything worked fine again for me.
I hope this helps. Sorry, if the explanation is not perfect; it is my first answer here.