I can't launch the Software & Updates center in Bionic Beaver. No video application will open. I tried to install the software center manually and got the following output:
neil@neil-ThinkPad-T420:~$ sudo apt-get install software-center
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package software-center is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'software-center' has no installation candidate
I'm not a technical adept and can barely follow simple terminal instructions. I need help.