Automatic installation of sqlserver and .net framework

This is typically done by coding a so-called bootstrap installer, and that is a simple Win32 application, typically coded in C++ which doesn't require ANYTHING to run on the fresh system.

That application would then test for presence of required resources, which in your case is to test .NET Framework and MSSQL installations.

You can detect presenceof .NET Framework, including precise versions installed, by inspecting registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework

MS SQL Server creates registry key:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server

, and under it you can inspect installed versions.

You can access registry from Win32 application by using WIN API, without need of any specific libraries and frameworks, so that will work for sure on a fresh system. If that application finds out that .NET Framework is missing, it can spawn a process running the .NET Framework installer, and then inspect process exit code to check whether installation went good. Same is with SQL Server - if it's missing, spawn a process with its installer and then inspect its return value.

In both cases refer to MSDN articles explaining return codes of these installers.

Once both installations went well (or components were initially present, so installations have been skipped), you spawn a process to run your installation, which requires these components to be in place.

Zoran