Refer below article.

The 'Microsoft.ACE.OLEDB.12.0' provider is not registered on the local machine.

nice step by step description! thanks.

What about the version of oledb provider to use in code...12.0 is outdated ????

I can see provider16.0 now.... so in the code which provider can i use so that it runs on all machines old and new 32 and 64 with old and new office versions?

You need to download the Microsoft Access Database Engine 2010 Redistributable from the link provide in the article.

Once you Download it will prompt you to select the architecture i.e. 32 BIT (x86) or 64 BIT (x64) and install it.

 // if the File extension is .XLSX using below connection string szConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;                       "Data Source='" + szFilePath +                       "';Extended Properties=\"Excel 12.0;HDR=YES;\"";

But in my code the connection string should be 12.0 ?? or the latest 16.0 ??? the provider

It should be 12.0