Lost access to my wordpress account

Hello,

We’ve been experiencing a problem with a specific plugin in the Suffice theme by Themegrill, resulting in the loss of our website (lesclefsdureve.com) and every wordpress accounts we’ve created until now.

We already know about the issues with Themegrill and we’ve already done some backups for our website.

However, not being able to access any of our previous accounts is a serious matter for us, we would appreciate any help for recovering them.
We’ve already tried to use the “recover your password” option for each of our accounts, without any success. We always get the “unvalid mail adress/username” message.

Moreover, even if we have some fresh backups, we’ve never tried to recover our website from them. Could you, if you please, provide us with some links containing informations about this process?

Thanks in advance, awaiting for your help.