[Update: Also see this post for tips on how to get your icon back.]
Since the latest update to the Google Earth client, we have recently had a number of people contact us saying that their Google Earth icon has disappeared. In some cases they have tried to reinstall Google Earth from Google’s website without success.
We believe the disappearing icons is due to Google Earth doing an automatic update and deleting any icons you have pinned to the desktop / start screen or task bar and not restoring them correctly to those locations. So in some cases you will find that Google Earth is still installed, but you need to re-pin the icons to your favourite locations. In other cases, the Google Earth automatic installer has failed and you need to reinstall it.
The standard way to install Google Earth is called an on-line install and is initiated from Google’s main Google Earth page. It downloads a small installer first which then downloads and installs the rest. Sometimes this installer runs into problems and a solution that usually works is to use the offline installer instead. Just go to this page and select the latest version and your OS.
We recommend that everyone use Google Earth Pro, as it has a few extra features and is now free. If it asks you for a licence key, just use your email address and the key: GEPFREE.
Never download Google Earth from anywhere other than an official Google site.
If none of the above works, take note of any error messages and try posting your problem in the Google Earth help forum.