A family of Microsoft word processing software products for creating web, email, and print documents.
When you click the Restore button, do your choices change to Maximize and Minimize? If so, then perhaps you just have the window sized to fill the screen; you can resize it with the mouse.
If the issue is that the document disappears when you Restore, then very likely it is opening offscreen and you can bring it back by opening another window (any window), right-clicking an empty area of the Taskbar, and choosing Cascade Windows or one of the Tile options. This should bring the window back in view; move and size it to your preference, then close Word, When you reopen Word, the window should be where you left it.