"Oops! Page Not Found."

[yojoe]

Try below steps
1. change theme to GS default one
2. disable all plugins you have installed
3. in settings tab make sure you have entered right website address
4. edit .htaccess file in your GS instance root directory, and make sure RewriteBase points to the right directory
Make also sure that above GS instace dir, there's no htaccess file from earlier installation, that overwrites rules in nested directories.

btw. if a plugin seems not working correctly, just delete its files from /plugins directory