Cannot Access Admin

I have been using this plugin for almost a year on 15 different WordPress sites I have in my server and I make weekly backups of all the sites and, on Sundays I download them all to my computer. Everything was working fine until this last Friday when Three of the sites went to backup and now I cannot access the admin area of any of the three.
I disable the plugin in the rest of the sites and They are working fine. But if I try to access ahgs.gob.mx/wp-admin nothing happens.
What can I do?
Thanks

https://ww.wp.xz.cn/plugins/backwpup/