Originally Posted by
Impavidus
10.04 is end of live (except for the server edition, but I don't know whether skype is included in the server edition). Skype is available in the repositories for 12.04, and also in the newer versions (at least, for the time being. With skype being owned by microsoft it may end one day). Lubuntu doesn't have LTS versions, so no reason to stay with 12.04, unless your hardware is too old. It's best to use a supported version anyway.
You interrupted the upgrade whilst it was still downloading packages, before installation started. Therefore nothing has happened to your computer. You still have a clean up-to-date 10.04 installation, for as far as an end-of-live version can be up-to-date.