How can i create a customized wordpress theme. Any software available for this?
There is no software for creating custom theme. You will have to design and program it.
There are some themes that let you make modification choices via admin pages - eg. weaver - but for a truly "custom" theme, as previously said, you need to get your hands dirty in your text editor.
After reading the Codex, try, and if you run into problems please start a new thread.