Creating completely new WordPress site from old WP one

Are you migrating the existing site from WordPress 3.5 to 3.8.1? If so, you shouldn’t need to create a new install, you can just upgrade the existing installation of WordPress to the latest version. Follow this guide for upgrading your install.

Switching to a new theme should be equally simple – assuming the new theme is properly written and you aren’t using a whole bunch of customizations built into your current theme.

When you say “even the structure will be different” what do you mean by this? If you’re making changes that will cause the URLs for posts and pages to be different, you’ll want to look at using a redirect plugin such as Permalink Finder.

Thank you (@Christiaan Conover) for your reply, but the new website will be different in (categories, tags, new pages, new menu) that’s what i mean by completely new, so i’m not upgrading or migrating.

But in the other side i need to use all the content from the old WP site ( the data itself as a raw martial e.g: if i have 1000 post i need to use them in my new site, i don’t need to enter them again instead reuse them)

I hope that i make it more clear.

Thanks

So you want to use all the posts and pages from the old site on the new site, but you’re changing the taxonomy? If so, you should still be able to do that on the existing site. You may want to set up a locally hosted development site for testing and configuration, and then port that back to your production site. However, there shouldn’t be a need for a completely new site. Are you moving the content to a new domain, or keeping it at the same location? If you’re moving it to a new domain, you’ll need to set up a redirect from the old one to the new one to avoid search ranking degradation, but if you’re keeping it at the existing location you should be able to use the existing install and set up redirects using either .htaccess, or a plugin like Permalink Finder to have clean redirects and avoid 404s.

again, thank you for your reply (@Christiaan Conover).

I have a local development environment and i will try as you say, also i’m keeping it in the same domain not moving to a new one, the only change as i said before is a ( new page structure,categories,tags) but the content will be the same.

Ok. You can either stick with your existing install, or copy the database from your current site to your development site, make all the modifications in development, and then wipe out and do a fresh install of WordPress on your live site and import the database from dev. Either way is fine, but if you opt for the second method you’ll want to make sure you have absolutely everything backed up first, in case something goes wrong (you should have backups anyway, but especially in this case).

Ok, thank you