@joanja ODD probably stands for Optical Disk Drive (your CD). It does sound like your computer cannot find an OS. You need a bootable disk so that your computer can start. Try to download an executable Live version of one of the many Linux distros. I use Puppy Linux whenever I try to recover data from HDD. Once you have that disk your computer most likely will boot up. Then you can try and see if it allows you to access your HDD. If so you know that it is an OS issue, not a hardware issue. If not, you are having a failed HDD. This may all sound like a lot but it is not. Just remain systematic and do one things at a time. This way you won't get confused with trying to many things at once. Stay away from things like this " I should change SATA from AHCI to ATA or IDE" for now. It worked before and those settings do not impact your computer issues right now.