Most likely problem is that server firewall blocked you, this can happen if you try to login to any service (cPanel, FTP, mail etc.) with wrong login details. When this happen your IP will be blocked in firewall and you will not have access to anything.
Easiest way to check this is to try to load site from diffrent IP/network or just test it over online tool like: http://downforeveryoneorjustme.com/ if is showing that site is online then your IP is just blocked by server firewall and site is working OK.
Please open support ticket requesting IP unblock. To see your current IP please visit this site: https://www.whatismyip.com/