How can I turn on Finder?

There really is no way to turn off Finder - Finder is your desktop. You can try by going to the dock and click on this icon which should open a new Finder window. To open Pages, simply go to the Applications folder and drag the Pages icon to the dock for one click access.

Finder is always on and can't be turned off. Are you, perhaps, referring to the Dock? Please explain.

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Where are your documents stored? You don't need to launch the Pages app to open documents. Simply find one (in the Documents folder would be a guess) and double click to open it.

If you can't open a Finder window, then try to reset it: with Finder/desktop active, hit these keys: Command + Option + Esc. You will see a window giving you the option to force quit/relaunch Finder - do that and see if that takes care of it. Also actually quit Pages by using Command + Q or the Quit option under the Pages File menu.

Okay, it's time for some info:

Which OS version are you running?

How much RAM do you have installed?

How much empty drive space is on your hard drive?