where to find the PPA's of the following:

Could you please rephrase and clarify your question?

Which Kubuntu package or packages are you trying to install?

You don't need a PPA to switch between Kubuntu and Ubuntu.

It is just a matter of installing the right Ubuntu packages.

For example: here are examples of different packages for installing different desktops in Ubuntu:

$ sudo apt-cache search ubuntu-desktop
ubuntu-desktop - The Ubuntu desktop system
edubuntu-desktop - educational desktop for Ubuntu
kubuntu-desktop - Kubuntu Plasma Desktop/Netbook system
lubuntu-desktop - Lubuntu Desktop environment
xubuntu-desktop - Xubuntu desktop system
$

Am using kubuntu 12.10.(64) I had a few corrupt PPA's in Software Sources, discovered after running apt-file update. Then ran Muon Updates , it reported Unable to download the following packages:
Failed to download gpgv:/var/lib/apt/lists/partial/extras.ubuntu.com_ubuntu_dists_quantal_Release.gpg Failed to download gpgv:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_quantal_Release.gpg Failed to download gpgv:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_quantal-updates_Release.gpg Failed to download gpgv:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_quantal-backports_Release.gpg Failed to download gpgv:/var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_quantal-security_Release.gpg Failed
to download
So I was trying to correct this - am no expert with Linux, so maybe I asked the wrong question?
Sorry for the mixup, all I want is to correct the PPA's.

https://help.ubuntu.com/community/PackageManagerTroubleshootingProcedure

Please post full Terminal output here:

https://answers.launchpad.net/ubuntu/+question/240479

Archive.ubuntu.com isn't a PPA. It is an official repositories managed by Canonical.

A PPA is a (p)ersonal (p)ackage (a)rchive and holds deb files made by joe somebody for their own use.

Why would you think a URL of the official repositories was a PPA?

I am just a relative beginner using Ubuntu - this is all way over my head. Have removed all PPA's from my Software Sources, restarted Muon, & selected 'Check for Updates'. I will be satisfied with that. Thanks for your help, I appreciated it.

I suggest studying these guides:

https://help.ubuntu.com/community/ExternalGuides