Can I install WordPress offline?

If you are on a Windows machines, you could easily setup a local server using WAMP or XAMPP.

Then download the WordPress and install it on your local server. Going offline only cause you trouble if your theme or plugins is using any CDN or depends on another server for accessing the resources. Say for example, if your theme is using Bootstrap framework, there’s a high chance that the developer might have used a CDN to speed up the loading. In such cases, there’s a need for internet, if not available would show broken layout or something when you try to access the website from your local server.

Regarding installation of WordPress on another PC and copying it back, yes you can do it and will work. Keep in mind, you need to copy both the files and database. And needs a couple of things to be changed:

1. Site URL. Eg: the other PC’s local url might be http://localhost/abcwordpress/ and you might have setup in http://localhost/test/. In that case, the site URL needs to be changed. You can change it in wp_options table in your database(after you import the database that copied from the other PC).

2. Absolute URLs. Sometimes, certain plugins stores the full urls in database. So even after you changed the site url, certain urls in the page would fail. Means, it would be still pointing to the other PC’s url (eg: http://localhost/abcwordpress/) In such cases, you need to do an entire search and replace to replace the URLs in database. For this, you could try using a plugin like Better Search Replace. And some slider or drag & drop content building plugins provides their own version of tool for searching and replacing urls. As they might store the URLs in a different way. So you have to use that too.

3. Database credentials. If you are copying the files, the wp-config.php would have the database credentials (db name, db username, db user password) different. Make sure you change it with that of the db in your PC’s.

4. Directory name in hataccess. Sometimes, the htaccess file in the main folder would have the folder name in it. Eg:

# BEGIN WordPress
# The directives (lines) between "BEGIN WordPress" and "END WordPress" are
# dynamically generated, and should only be modified via WordPress filters.
# Any changes to the directives between these markers will be overwritten.
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /abcwordpress/
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /abcwordpress/index.php [L]
</IfModule>

# END WordPress

Here, the abcwordpress might be the foldername. So if you are storing it in a different folder (and the url to access is like this : http://localhost/test/ , then you would have to change it to :

# BEGIN WordPress
# The directives (lines) between "BEGIN WordPress" and "END WordPress" are
# dynamically generated, and should only be modified via WordPress filters.
# Any changes to the directives between these markers will be overwritten.
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /test/
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /test/index.php [L]
</IfModule>

# END WordPress

I think I covered the major things that you have to keep in mind.