Sorry to hear that, it sounds like you will need to restore your forum from backup
I must be missing something with the SendGrid setup. I created a domain for use, had SendGrid authenticate, and created the "reply" name (just a name, no real email since the domain is for NodeBB notifications only. Seems OK on the SendGrid side.
In NobeDD | Email, I have SendGrid selected and the email address. As there is no "real" account, how can I use a password? is it required? Test emails do not work.
Can you take a picture of your configuration in the ACP?
@tmiller you must have "use external server" enabled. That enables the SMTP transport.
As for the username and password, these are required and should be provided by sendgrid. They may be your sendgrid login credentials but I'm unsure as I've never used sendgrid.