When I install a plugin in Eclipse everything goes well. But after restarting the new plugin is not visible. I have tried it with different plugins, but they have all the same problem. The only place where I can see them is when I look at "What is already installed?".
What could be the problem?
You could be in a custom perspective in which the plugin commands are not set to be visible (hence no menu, no view, ...). See this question for more on perspectives.
Can you see your plugins in the <eclipse>/plugins and <eclipse>/features directories?
Can you check your "Error Log" view and see if there is any error message?
Can you see if the Preferences reference your plugins?
You can also try re-launching Eclipse with the -clean command line argumen
I seem to be having a similar problem and I am using Windows 7 64 bit - I have installed quite a few packages (e.g. SVN integration, Git integration, Maven integration) but none of them show in my perspectives or views.
EDIT: the reason I seem to be having those problems was because I had eclipse installed into C:\Program Files (just to make my files more organised), but I was not running it as administrator. Once I run it as admin, it seems to install the plugin correctly and show it when I reload eclipse.
Have you tried running Eclipse with the -clean argument ? You need to do this only once and not every time you start Eclipse, you it is recommended to do so after a plugin installation.
If that doesn't help, verify if you have privileges to write onto the features and plugins subdirectories. The plugin installation process requires the write privilege, but I've never seen a plugin installation succeed without one; still, it is worth checking for.
This issue and its solution is described in a DZone article and at the nWire blog.
It all boils down to these two options:
I had a problem one time where I was running eclipse with an old jre - it worked but plugins that needed jre6 didn't load. Do you have a recent jre in your path and as your java_home?
This thread describes the problem you are likely having, where p2 gets confused and sees that your features are installed but the plugins are not.