There are multiple ways to connect by FTP to a host. Easiest way is to use internet explorer/firefox or any other browser as FTP browser.
You just need to type following in the web browser:-
ftp://YourFtpUser:YourFtpUserPassword@yourdomain.com
If you are connecting FTP account using user@yourdomain.com then you will have to use URL like this:
ftp://YourFtpUser%40YourDomain.com:YourFtpUserPassword@yourdomain.com
You need to make sure that FTP username is YourFtpUser%40YourDomain.com
This address is URL-encoded and comes from YourFtpUser@YourDomain.com where @ has been substituted with %40, which is the ASCII code for @.
If you still have problems connecting by FTP, it is possible that your outgoing TCP port 21 is blocked by your local firewall or Internet service provider. If this is not the case, then your FTP server might be unreliable and you should transfer to a stable FTP service provider.
Please visit http://www.milesweb.co.uk/hosting-faqs/check-if-ftp-port-21-is-blocked/ to check if Port 21 is blocked.