Hello world and simple led blink does not work

You have a DDR controller in there in addition to on chip memory. Delete it. Make a backup copy before if you want to keep it. In QSYS, assign base addresses. Make sure your Nios has on chip memory assigned for reset and exceptions. Generate files in QSYS. Make sure your qip file has been added to the Quartus project. Compile in Quartus. In the software build tools, delete your BSP project and re-create it. Move your software source file(s) somewhere else if it has anything you want to keep. Delete your application project. Create a new application project and be sure to use Hello World (small).