Forum Thread: How Do I Reinstall Kali Linux to "Undo" Some n00b Mistakes?.

I've been trying to get the hang of Kali Linux as a command line virgin, and as expected I made a mistake by editing some file I wasn't supposed to. Everytime I would update/install I would get

Ignoring file 'some-ppa.list.save.1' in directory '/etc/apt/sources.list.d/' as it has an invalid filename extension
Type 'gpg' is not known on line 1 in source list /etc/apt/sources.list.d/signal-xenial.list
The list of sources could not be read.

There were 3 files in /etc/apt/sources.list.d/ which are nordvpn.list, signal-xenial.list and signal-xenial.list .
the last whuch I altered is not there anymore after I used some such command.
I'm just trying to freshly reinstall kali.
please help, thank you.