Trash missing from Dock

Solution 1:

You shouldn't be able to delete the Trash folder from your Dock. To put it back, reset your Dock settings:

1. Open Terminal (/Applications/Utilities/Terminal.app)

2. Run the following command to delete the Dock preferences file:

   rm ~/Library/Preferences/com.apple.dock.plist
   

3. Log out and back in.

Solution 2:

I think you should first use killall Dock using Terminal.

This will reset your dock. If this doesn't work then you should download a 3rd party application such as DragThing.

Then logout and log back in, and start using DragThing.

If you need more help you can go on these websites : http://mac.bigresource.com/OS-X-Leopard-System-and-Trash-icons-gone-from-dock--t9R58eDJO.html

https://discussions.apple.com/thread/1494553?tstart=0