Regardless of the reason your account was restricted, the only way to get out of this restriction zone is by contacting bet365's customer support. Even if you have no idea why your account has been restricted, you should still contact customer support to get an idea so you can open it back.
Simply download a reputable VPN and connect to a server in a location where bet365 is permitted, such as the UK or Germany. Then, when you head to the bet365 website with a new IP address, it will give you full access to the betting site!