First you should check if there are any network issues, the article linked below might be helpful before completing this step:
Confirm the FTP service is not running
Check the status of the FTP service by running the following command in SSH:
mediacp status
mediacp start ftp
mediacp status
If FTP is still not running, then something is preventing the service from starting.
First you should run a software health check to see if you see any errors relating to your hostname. Hostname issues will cause FTP not to start, if you see this message please follow this guide:https://www.mediacp.net/portal/index.php/knowledgebase/133/Hostname-not-resolving-FAILCheck-system-hostname-is-resolvable.html
If that is not the case then running this command, you will be able to see the various warnings and errors that are preventing the service from starting. Open a helpdesk ticket and include the output so our team can identify the issue.
/usr/local/mediacp/proftpd/sbin/proftpd -c /usr/local/mediacp/proftpd/etc/proftpd.conf
If the service is running but the FTP login username and password is not working.
The following guide will help you regenerate all FTP account logins.