The Squish IDE makes it easy to add and remove views from perspectives, and to move views around within a perspective.
Restore a perspective to its original state
To restore a perspective to its original state, make sure that Squish is in the relevant perspective (by clicking the Window→Open Perspective... menu option to change to it if necessary). Then click Window→Reset Perspective.... This will pop up a confirmation dialog and if you click the OK button the currently showing perspective will be restored to its original state with all its original views.
Add a new or missing view to a perspective
If you want to add a view to the current perspective (either one that was originally in the perspective but was removed, or another one entirely), click the Window→Show View...→Other... menu option to invoke the Show View dialog and in that dialog click the view you want to add and then click the OK button to confirm. Once the view has been added you can drag it to where you want it if the default position isn't where you want it to be.