It sounds as if you are in full-screen mode. Pressing the Esc key should get you back to normal mode. If that doesn't work try moving the mouse pointer to the top right of the screen and clicking on the double diagonal arrow.
If you can currently see your menu bar, then just click the "+" in the top-left of the Safari window. Counter-intuitively, it will probably make the window smaller. If you can't see your menu bar, move your mouse all the way to the top-right of your screen, and click the blue icon to take you out of fullscreen.