Eclipse has major structural problems with uninstalls, which aren't really fixed even the latest luna. But don't worry, there are a lot of workarounds.
What you can do now and in similar situations:
1.
If you can even uninstall something, you won't get back its previous state before the install.
Because of it I use Eclipse normally with a trick: I store my main Eclipse install directory in a git repository, and so I can always switch back with a single command. But it is only a trick.
2.
There is a big chance, that only your workspace directory is damaged, and not your Eclipse. In this case you can solve this problem by reinitializing your workspace: make a backup, delete everything, recreate your workspace directory and finally import again your projects.
(For similar reasons it is also an useful trick to save your workspace metadata in a git repository as well.)
3.
In Eclipse, the menu items are created by modules. If an eclipse module is installed, it creates the changes in its internal configurations which create the menu items.
After a restart, Eclipse tries to restore your gui, and thus re-open its panels. But if a module uninstall is also happened, then its panels aren't restorable, resulting exactly your problem.
So, simply close the bad panels and try to reopen them. Sometimes it also works.
In short: recreate your workspace, it will probably help. And next time, use Eclipse with some good and frequent backup (I suggest git).