Page Cannot Be Displayed error

99% will be because of these reasons:

Firewall or router blocking the secure port. (Typically 443). 
Make sure that port 443 is open and allows traffic through.

Port 443 has been assigned for SSL by the web server. 

In IIS you will need to enter 443 into the SSL port on the Web Site tab of your site. In Apache you will need to specify :443 in the virtual host section pertaining to your site.

Private Key Modulus does not match the Public Key Modulus. 
If you submit the key file and the certificate file to support, we can check to determine whether the moduli match.  If they do not match then it is likely that there has  been a mix up with their private keys or the private key has been deleted.  If the private key cannot be found you will need to start again and create a new private key and CSR and have the certificate reissued.

Web Server is not configured properly.  
There must be a unique IP address assigned to the web site.

In IIS the IP address detailed in the IP address field on the Web Site tab of your site must be specified in the Advanced section (click Advanced next to the SSL Port entry).  If All Unassigned is present, remove this and add the IP address.  You cannot use Host Headers in IIS. Unix based web servers (Apache, control panels such as Plesk, WHM, Ensim) must be in IP based mode and not in name based mode.  A unique IP address must be specified in the virtual host section of the site.

Only 1 IP per certificate or conflicts will occur.

DNS Issues.
A site will either have an internal or external IP address.  Find out which.  The IP address must route to the domain name *somehow*. Can the site be accessed via the IP address?
If the domain name has been recently purchased then the DNS records needs to propagate (24-72 hours). If an internal IP address is being used, then a Network Address Translator (NAT), Firewall or router must be routing the internal IP address to an external IP address for the site to be found externally.
Some web servers require a physical reboot.  Leave this option to last as it can cause disruption to service levels of the hosting company.