SOLVED - How can I reinstall essential packages?

[KIMW]

How can I reinstall essential packages?
I've messed up my system and now I've message errors:

E: Package 'autoconf' has no installation candidate
E: Package 'automake' has no installation candidate
E: Package 'libpcre3-dev' has no installation candidate
E: Unable to locate package libnl-3-dev
E: Package 'libsqlite3-dev' has no installation candidate
E: Package 'libssl-dev' has no installation candidate
E: Package 'ethtool' has no installation candidate
E: Package 'build-essential' has no installation candidate
E: Unable to locate package libnl-genl-3-dev
E: Unable to locate package libgcrypt20-dev
E: Package 'libtool' has no installation candidate

[smurphos]

What does inxi -r report back? You appear to be missing some Ubuntu repos.

[KIMW]

Thanks for helping.

Code: Select all

$ inxi -r
Repos:     Active apt sources in file: /etc/apt/sources.list.d/ubuntu-defaults.list
           deb http://ppa.launchpad.net/kubuntu-ppa/backports/ubuntu/ xenial main

[smurphos]

Try opening the Software Sources application and then under Offical Repositories click on Restore the default settings and then on Update Cache.

[KIMW]

Excellent! It worked.
On Software Sources application I had previously clicked on: "Fix MergeList problems", etc, etc, on the Maintenance tab but it did not do anything. With your help it worked this time. Thank you.

[KIMW]

Something else I'd like to ask if you can help.
On Home folder I have lots of stuff (especially when I show Hidden Files) which remained there each I was trying an application. How can I know which ones I can keep and which ones I can delete. And then how can I delete/remove them properly?

[smurphos]

Hi,

I wouldn't worry about them. The hidden files and folders in home are normally config or user specific data / cache files for your applications. You will occasionally end up with 'orphan' files in here but they do no harm and in general will take up very little disk-space. If you do spot something that from it's name you are sure relates to an app you have installed and emoved just delete the files/folders in the normal way. If you are not sure what something is for just leave it alone.

[KIMW]

Hi,
OK, thanks for your help again smurphos.
Bye.