Eclipse Find/Replace not working

I had a similar issue after using second monitor at work. At home I was wondering where is my Find/Replace window... it was displayed at the second monitor as I used it last time... Eclipse stores the last location of the dialogs for better UX.

So try to move the Find/Replace window by using your keyboard.

How to Move an Open Window with the Keyboard

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You can also try to reset perspective

Window > Perspective > Reset Perspective...

I had the same issue with Eclipse. My current version is Neon.3 Release (4.6.3).

This periodically happens where the Find/Replace does not work. Usually UNDO stops working also.

When this happens, Ctrl+F, Ctrl+Z do not work, and Undo Text Change and Find/Replace... are grayed out in the menu.

I tried the above solution Window > Perspective > Reset Perspective...

That fixed it right away!

Thanks