“[DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied” after installing SQL Management Studio?

I recently installed SQL Management Studio (which also installed SQL server 2016 to my local machine), and now am unable to connect to SQL server from applications on my machine. It will come up with the error message below:

"[DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied"

At this point, should I just uninstall SQL management studio/SQL server, or is there an easy way to resolve this issue without needing to do so?

Here is the code I am attempting to execute which worked before installing SQL server and SSMS.
                string connectionstring = ConfigurationManager.ConnectionStrings["B2BConnString"].ToString();

                OleDbConnection conn = new OleDbConnection("Provider=SQLOLEDB;"+connectionstring);

                string strSQL = "select [aliasname], [apikey], [password], [sharedsecret], [url], [isTest], [lastid] from ShopifyWSSetup as s Inner Join Clients as c on s.cno = c.cno where isactive = 1 and aliasname = '"+aliasname+"';";
                OleDbCommand comm = new OleDbCommand(strSQL, conn);

                OleDbDataReader reader = comm.ExecuteReader();
                if (reader.HasRows)
                    while (reader.Read())
                        apikey = reader.GetString(1);
                        password = reader.GetString(2);
                        sharedsecret = reader.GetString(3);
                        url = reader.GetString(4);
                        isTest = reader.GetBoolean(5);
                        if (!reader.IsDBNull(6))
                            lastid = reader.GetString(6);


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Connection string:
<connectionStrings> <add name="ExampleConnString" connectionString="Data Source=;Initial Catalog=Example;User ID=Example;Password=examplePW;Connect Timeout=30" providerName="System.Data.SqlClient"/> </connectionStrings>

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I uninstalled SQL Server 2016 which came with the SSMS. Now I only have SQL Server 2008 on the machine, but the error is still occurring.
Jordan JohnsonAsked:
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Éric MoreauSenior .Net ConsultantCommented:
Do you have a named instance? -> then you would need to specify it in your connection string (\NameOfYourInstance)

Could it be a firewall issue? Try disabling it for 10 minutes

Is the TCP IP protocol enabled in SQL Configuration tool?

Try adding "Network Library=DBMSSOCN" to your connection string to force using the TCP protocol.

Is the database local or remote to your process?

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Using sql 2008 configuration to make sure you did not alter/upgrade the installed instance. Often during install you can choose which components you are installing..

Pointed out by prior what information is missing.

the issue might be the new sql native client library installed.

Get and install the sql 2008 SSMSE version. Then it will help you trouble shoot the issue.
Vitor MontalvãoMSSQL Senior EngineerCommented:
Jordan Johnson, do you still need help with this question?
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Microsoft SQL Server 2008

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