How to show the Project Explorer window in Eclipse
Try to close Eclipse IDE and reopen it and
click on window->show view->project explorer
For me it was like this...
Window->Show View->Other->General->Project Explorer
Or
Window->Open Perspective->Other->Java (default)
try window->Reset prespective. remember your own settings will be resetted if any.
Open Eclipse IDE Enter "Project Explorer" on Quick Access (Search text box). Either select from drop-down or press Enter