Registrar issue, if I remember correctly. It was set to auto renew, but they didn’t do it, and I only noticed when my site was suddenly a placeholder page.
I had that 20 years ago. Credit card expired, registrar didn’t tell me, and I lost a 4 letter .com.
After that I moved to hosted Mail (yahoo, then gmail) as I felt it was more reliable. Now I ensure I have more than one email on file if possible with any account. Same with phone numbers.
