Disk not appear on utility disk

If it doesn't appear at all that is pretty terminal. You can spend $100 on a utility such as Diskwarrior which might, or might not, be able to do anything. For certain I would never trust the drive again. If you have recent backups then just look into getting a new drive. People posting after me will likely tell you to get rid of a 10 year old model and buy something newer but I love the old Macs and they do what I need. The nice thing about the old ones is you can do a lot of repairs yourself. Drop a 1TB drive into that for <$100 and you're back in business. Make it a SSD for about $100+ and it will be a lot faster.