how can i enable the menubar and titlebar?

I have installed the latest Ubuntu version obtained on the website. but when using it i have notice that in the file explorer the menu and title bar are not visible.

is this because they have been removed or is there anyway to get them back???

Yes, they have been removed. Gnome has moved to a different look, without title and menu bars. The main menu is now hidden under the button with the "hamburger" ≡.

No, there is no way of returning to the old paradigm less than changing desktop environments and/or applications. Many other graphical file managers maintain the traditional menu bars and legacy title bars, e.g. thunar, caja. Forks of core gnome applications exist with the aim to preserve these, e.g. the Mate desktop has Pluma, forked from the text editor Gedit, Atril, forked from PDF viewer Evince, "Eye of Mate" forked from the photo viewer "Eye of Gnome"... Also the people over at Linux Mint foster legacy title and menu bars in forks of these applications under the project XApps. They have "xed" as editor, "xreader" as PDF viewer, "xviewer" as photo viewer, ...

These applications can be installed in the default Ubuntu desktop, although fully integrating a different file manager is quite a challenge. If you value the legacy menu bars and title bars, moving to Mate desktop probably makes most sense within the Ubuntu ecosystem.