Can you explain a little more when you say you say:
"When I try to edit the contents by clicking on the edit menu field from the index page nav area and I go through all the steps and nothing happens."
Are you re-entering the menu writer wizard?
Can you also tell me what version of MW and SAP you have?
You should not have to reinstall SiteAssist Pro and if you reenter the SiteAssist pro wizard then the content in the main content area should not get over written. As far as the styling, you should add your styles to the styles.css, this file does not get overwritten when you reenter the SAP wizard.