I want to share this for all those who cannot find why its not working.. Normally when you enter a Dot "." there should be a pop-up window as a code completion window but its like nothing ever happens in my situation and not fixed after restarting the IDE.
Here's the solution:
go to Tools -> Options menu.
go to insight options (search it there)
go to Code Insight tab, then select "Delphi (Classic code insight)" from the code insight manager ComboBox and uncheck the Code Completion option below it, and hit the save. that's it! Enjoy ;-)