Can't connect to new instance of SQL Server
You have installed a new instance of SQL Server, so you need to change the way you connect to that new instance.

Previously, you had a default instance, so connecting using any of these in the Server name: box would work fine:

localhost
.
127.0.0.1
&lt;any_local_IP&gt;
&lt;your_machine_name&gt;
&lt;your_FQDN&gt;


Now that you have installed a new instance of SQL Server, you need to reference that instance name as part of the connection string, so any of the above need to become the following:

localhost\MSSQLSERVER14
.\MSSQLSERVER14
127.0.0.1\MSSQLSERVER14
&lt;any_local_IP&gt;\MSSQLSERVER14
&lt;your_machine_name&gt;\MSSQLSERVER14
&lt;your_FQDN&gt;\MSSQLSERVER14