If this is a false positive, meaning that your access to your own site has been limited incorrectly, then you will need to regain access to your site, go to the Wordfence "options" page, go to the section for Rate Limiting Rules and disable the rule that caused you to be blocked. For example, if you were blocked because it was detected that you are a fake Google crawler, then disable the rule that blocks fake google crawlers. Or if you were blocked because you were accessing your site too quickly, then increase the number of accesses allowed per minute.