How to save contents for a new installation

First you take a backup of your database, this is where your content lives (except for media).
Now you reinstall all your files. Also delete stranger files.
Maybe you don’t need to restore your database, it all depends.
Install a plugin like “All in one WordPress security”

Thank you Ross.
Does this will include all images, media files and their positions?

You need to keep all the media files and images.
Keep their positions too.

When the security program does a scan it will tell you if any of your media files have been contaminated.

Thank you Ross.
Just to make me know if I understood:
I’m going to re-install a new WP website in a new directory, then I’ll link the new site to the old DB (wp-config.php and I think I should edit the DB directly because the DB will point to the old WP directory).

Then I’ll copy media files (wp-content/uploads) to the new WP directory.

Does this will restore the old content to the new WP website?

What I think you should do is just a little different.

You should delete all of these files and directories:
wp-admin
wp-include

ALL files in the root directory EXCEPT wp-config.php

In the subdirectory:
wp-content/themes
– keep your own themes
– delete themes twenty “everything”

In the subdirectory:
wp-content/plugins write down the names of your plugins.
Now delete them.

Now install a new set of wordpress files, all of the folders and files will now have the good and clean contents.

Now see if your website runs.
If it does not, then there are some problems in the database.

Otherwise you are up and running, install the plugin “All in one WordPress security” and “Server Security Scan”, run them.

Now reinstall your plugins.