How do i download PAGES on my desktop? I had it, then the machine was restarted and man pages was gone.

Pages does not install to your Desktop. It installs in the /Applications location on a Finder sidebar. You will need macOS Monterey 12.* or later to install Pages from the Mac App Store.

If you are on an older operating system, it will depend if you installed Pages with the same Apple ID at some point after Oct 2013, or if someone else (Apple, reseller, other user) installed Pages with the Mac.

If it was you in the second paragraph, and on Mojave (10.14.*) or later, you can launch the Mac App Store, sign in with the same Apple ID you used to install Pages beforehand, and then press cmd+0 (zero) to open the Purchased panel. Pages should be there for installation. There may be one or more dialogs which you do not click Cancel and the last one will offer to install the last version of Pages compatible with the operating system in use.

If on macOS older than 10.14.*, then you will want to launch the Mac App Store, sign in with the Apple ID last used to install Pages. Then you press and hold the option key while clicking the Purchases toolbar item. If the Pages icon is present you may see install or upgrade and the rest will be as the preceding paragraph.

If Pages was pre-installed by Apple or another entity, then you are done because Apple does not provide separate downloadable full installers for Pages, Numbers, or Keynote.