dock is disappearing on my mac os x version 10.7.4?

Happened to me too, It was already turned on 😟, I turned it off, on, and it was there again- Good Luck

The disappearing dock your answer was absolutely excellent. Right on the money. It's so hard sometimes distinguish you has the right answer and who has the wrong one. I thank you very much for giving me the answer on this today.

It happens to me when I use the wrong short cut, most have a pre programmed short cut to hide unhide dock.

Press - alt>cmd>d - usually brings it straight back.

Thanks! Problem solved (created by grandson accessing keyboard without my noticing!!!!)

The disappearing dock can be for any or many of the reasons given in previous comments. However, the missing dock that many people are experiencing comes mostly from Youtube.Com full screen with adobe flash. Fullscreening and using multiple desktops will make it disappear. I use a macbook air in clamshell mode often with an external screen. Both this, and fullscreening youtuve videos will cause anything from mouse fallout, trackpad dead, missing dock, or a complete computer freeze. It is more to do with youtube's keyboard shortctut deactivation (very trojan-like - in fact in the old days it would be considered a browser hijack). Youtube and many other sites including Facebook will deactivate your keyboard shortcuts such as command and V and command and X, or command and T for a new tab (wont work in many websites anymore because of javascript keyboard shortcut deactivation). This is also why with mobile such as ipad, the search bar and the virtual keyboard bounce around like a yoyo when trying to type a search.

It is the modern method of using AJAX and JAVA to control the device of the user and limit what the keyboard can do, which is causing the problem.

All other cases will be under the 'overlooked settings' category as has been explained in many previous comments in this thread. If it isnt a setting, then what i have explained above is the true root of the cause

So I ran the code posted by Morgan I believe..I think its a bug with silverlight if you are running it to watch videos online. It asks if you want to keep the video full screen mode after exiting full screen. I figured that out from having the issue via Amazon Prime

Thank You.

something as simple as hitting escape after hours of trying to get my dock back....thanks!

Thanks for this - it worked and was a much better (and safer) solution for me than tinkering with Disk Utility. 😎