I am with KVCHosting and after spending a good few months with them i have come onto the computer today to find that they have randomly decided to IP ban me from their servers, meaning that i can access my sites or their homepage but the sites on the server are accessible to other people. What can i do other than to send them an email that is going to be placed into a ticketing system? Should they not have sent me an email or something to tell me that the ban was in place? I have no idea why they have done this as i have not broken one rule and the server is paid well in advance....
Unless you have given them reason to ban your ip from all their servers they probably have not. Assuming you get a 401 access denied page, could be they have had hacking attempts, dos attacks etc and temp blocked a range of ip's that includes yours, could be an error or corrupt config file etc. If you don't get a 401 page could be your isp has a problem with routing, DNS, your firewall, or other reasons. Contact them by email and tell them what happens and what error code you get when you try to access. You might of got more help if you had of posted in Site & Server Administration sub forum tho.
Usually the ip address get banned automatically by the server if you had any failed login attempts. This is a ddos protection installed on the server. This is temporary though. Do a tracert from your pc and check the result, this will give you the right idea of whats blocking you.