Why certbot doesnot create automatically an ssl version of the apache conf for my site?

Hi @refschool,

Do you mean that the HTTPS virtual host for your previous site was created and then later removed, or that you obtained a new, separate certificate for a different virtual host and didn't get an appropriate virtual host configuration file for the new certificate?

In the second case my guess would be that you used certonly, which does not attempt to install the certificate or configure the web server.