If you have access to the .htaccess file (this is where the ip addresses are blocked via all-in-one-wordpress) then you can edit this file to replace and/or add an additional line here.
Only change the lines concerned!:
<IfModule ...
Allow from <Insert-Your_IP_ADDRESS_HERE>
</IfModule>
And then also from:
<IfModule ...
Require ip <Insert-Your_IP_ADDRESS_HERE>
</IfModule>
You can go and search for your external ip address by using:
curl ifconfig.me
However when you do have access to the page don’t do this anymore.