You can find an icon for your hard drive in many places.
- The easiest place is on your desktop. By default, every disk volumes has an icon on your desktop. Two issues that may arise are:
- You've changed that default. You can turn it on again by going to Finder->Preferences->General and under "Show these items on the desktop" put a checkmark in the box for "Hard disks".
- You can't see your desktop because you have too many windows open. Either close the windows, or hide applications, or use Exposé to show the desktop. The Exposé hot-key to do that is normally F11, which you may have have to type as fn-F11.
- Another way to see hard drive icons is to go to Finder->Preferences->Sidebar and put a checkmark in the top checkbox, the one with the same name as your computer. That puts your computer in the sidebar (left side of a Finder window), and clicking on that puts a list of your disk volumes in the body (right side) of the Finder window.
- A third way is to open any Finder window and keep pressing command-up_arrow. Eventually you get to a window showing all your disk volumes (including a few artificial ones, like "Network"). This is the same window you got to using method (2) above.
There are some places where you can see icons that cannot be dragged elsewhere. Trying to drag an icon
from one of these places only makes the icon disappear in a puff of smoke, no matter where you try to drag it
to. Those places are
- the Dock (as you've already discovered), and
- the Finder sidebar (left part of a Finder window). I'm guessing that's where you dragged Applications from to make it disappear too.
In particular, dragging an icon from the sidebar to the Dock doesn't put the icon in the Dock; all it does is remove it from the sidebar. Likewise dragging an icon from the Dock to the sidebar only serves to remove it from the Dock. You restore icons to these places by dragging them from the desktop or the body (not the sidebar) of a Finder window, or the proxy icon (the little icon in front of the window title) of a Finder window. Once you've found your hard disk icon again, open it up to find an icon for /Applications, which you can drag back to your sidebar if you want.
If Applications is really in the trash,
Do Not Empty the Trash. Open the trash, select Applications, and apply the menu command File->Put Back to put it back where it came from. If what you have in the trash isn't really the /Applications folder but only an alias to it, there's nothing to be concerned about and it can be safely deleted. Use Get Info to find out what it really is.
When you're trying to add an icon to the Dock, don't drag it onto the Trash icon. Drag it
near the Trash icon, which will coax the Dock into moving icons apart to make room for a new icon. Drop your new icon there.