I was in the middle of reinstalling MacOS when the computer was shut down. Now when turned on I get a File folder with ? On it. Any suggestions?

I was in the middle of erasing the old IOS system and reinstalling. During the reinstall I looked at the reset area and clicked it. Then click restart. This was in the middle of the reinstall. Now when start up, I get a blinking file folder with a ? on it. Any thoughts as what to do? Command R and shift Command R do not work.