www.... does not work in my domain but *.domain.com works please help me to solve this problem
www.mydomain.com does not work
Without knowing the domain, we can't really check the DNS to see what is or isn't valid. With that, my suggestion would be to make sure your DNS looks like:
A @ DROPLET_IP A * DROPLET_IP CNAME www domain.com
... and that your VirtualHost (Apache) or Server Block (NGINX) is setup properly. Of course, these are just suggestions. We'd need to check your DNS and look at the configuration if the DNS matches the above.