I have a Spanish OS based on 11.04 called 'Darwin OS'. After installing it, the setup file still existed on the desktop. So, I opened it to see what would happen. It got stuck at Detecting file systems so I just closed it. Later, I started having a lot of problems with the OS so I decided to switch to the normal 12.04. But when I booted from my USB, it said An Operating System wasn't found. Try disconnecting any drives that don't contain an Operating system. Press Ctrl-Alt-Del to restart. I tried that a couple of times but nothing happened. What should I do?