How do I access the Volumes directory in Macintosh HD?
We need more specifics about what is going wrong. Do you have admin privileges on your computer?
Have you tried ⌘-⇧-G from the Finder and then typed /Volumes in that window?

You can also open a Terminal window, type cd /Volumes and then if that works type open . (a period).
If none of those work, then you need to set up that account with privileges to access root folders, but I think it should at least ask you to authorize when you try Go to Folder...

Edit: Just a guess, but from the Finder, click on the Home icon to get to your user menu. Then go to the View menu &gt; Show View Options (or press Command-J). At the bottom, click to show Library folder. (If you don't see this option, you probably have the wrong folder selected.)