I added some DNS from SendGrid and also set up my webmail, but after that I could not login to my cPanel, I remember my username and password but they are invalid. I go to Manage Hosting (https://myh.godaddy.com/#/hosting/all) and noticed that my website has gone!
I then deleted new DNS that I've just add and tried to access to GoDaddy with another browser but nothing changed. Was my website deleted or not? How could I get my backup if I could not get access to cPanel?
Changing DNS should not delete your website or hosting account from displaying in the GoDaddy dashboard.
Is it possible that your account expired? Are your payment details up to date? I don't think any of us here have the access or info to help determine what is up...
I would get on the horn with GoDaddy and try to find out what happened. 😉