Question: I am using Ubuntu 12.04 LTS and want to upgrade it to 12.10. Please send me step by step info for this process. Will my personal data be lost? If yes, then how to protect it?

Answer: 
<http://www.ubuntu.com/download/desktop/upgrade>

This has the step by step instruction for using the graphical Software Update. Very easy to use.
use this command:

sudo apt-get dist-upgrade

your home directory will remain the same with current (before update), also your program/software installed. So, you do not worry about loss your data.