I have an Ubuntu version loaded. I want to install latest version without formatting and loss of data. Update Manager does not show upgradable version to install. If I download and install the latest one, will it damage my existing data? Can it be loaded under upgrading system any other way?
You don't say which version you have, or which you are trying to upgrade to, but you can find more information on upgrading Ubuntu here. In general you can upgrade without losing data (although you should always take backups, and read the release notes beforehand for exceptions and other comments). There could be many reasons the upgrade isn't working. Are you able to install packages from the current version you have installed? That would be a good check whether your package management system is working right, for example.
Ideally Not. You should install all upgrade packages of current version. Then do
You can more info here