TL;DR --> I want to know how to make an old account show up after reinstallation of Ubuntu so that I can log in to that account and not have to reinstall all the other software I had installed on that account already.
I installed kubuntu-desktop once my ubuntu installation was done. I became unhappy with it and so I un-installed it.
To un-install it I re-logged in to the unity workspace stuff and removed all the KDE packages.
When I restarted my PC the ubuntu loading screen would show and then the screen would go blank, since I assumed that this means that the computer is not hung up and working I pressed Alt-Shift-F5 to open the shell. I couldn't find a way to make the greeter show up. I checked whether or not it was installed, and it was installed.
Since I couldn't find a solution to it I loaded the LiveUSB and reinstalled Ubuntu. But this time I couldn't use the already set up account (abc) again when it asked me to make an account, so I made a new account abc_new
After installation the login screen came up just fine but I was expecting account abc to be part of the list of logginable accounts. But its not there.
I want to know how to make it show up so that I don't have to reinstall all the other software I had installed already?
If your reinstall of Ubuntu from the LiveUSB included a format of your hard drive, and if you don't have a backup stored somewhere other than the hard disk you reinstalled to, your old account and software are gone. If that is the case, you will need to create a new account and reinstall your software. You can read your /etc/passwd file to see if your old account is listed. If the account name is not in the passwd file, then the account doesn't exist in your newly installed Ubuntu.
$ cat /etc/passwd
or
$ less /etc/passwd