Replacing the nulled plugin with a fresh copy is a good start, but please note that we cannot guarantee it will remove the traces of any potential malware.
The translations are stored in your database, so removing and installing a new version shouldn't affect the existing translations.
Please create a full backup of the database and website then try the following steps:
- Access your site's root folder via FTP or cPanel
- Delete the current WPML plugin folder "sitepress-multilingual-cms" from the /wp-content/plugins/ directory
- Download a fresh copy from: https://wpml.org/account/downloads/
- Install it again from Plugins > Add new
- Activate it