Problem with Let's Encrypt cerificate

Are you sure ?
After 1 week all the certificates reset
I’ve just tried again to install let’s encrypt certificate on the domain and now there is another error:
Invalid response from https://acme-v02.api.letsencrypt.org/acme/authz-v3/3112075038.

Details:

Type: urn:ietf:params:acme:error:dns

Status: 400

Detail: DNS problem: NXDOMAIN looking up TXT for _acme-challenge.immobiliaremalmassari.com - check that a DNS record exists for this domain