If you have control panel or FTP access to your site, then first you can try copying the unzipped MaxGalleria plugin up to your plugins folder. This would hopefully allow your site to run. With MaxGalleria deactivated the addons would display a notice saying that they need MaxGalleria activated to run. If that does not work then your next step would be to change the name of each addon folder, such as change maxgalleria-albums to maxgalleria-albums1. The simple act of changing the folder name will make the location that WordPress is expecting to find maxgalleria-albums invalid and as a result WordPress would deactivate the plugin. Rename the addon plugins and WordPress should deactivate each of them.