Examine the book to determine what you need to repair. In all likelihood, it's going to be the hinge that needs tightening or pages that require resetting.
Pour a small amount of glue in a straight line on a piece of waxed paper. Roll a knitting needle in the glue and gently tap off any excess.
Pull the loose hinge away from the front or back board that serves as the cover of the book. Do this as gently as possible.
Run the knitting needle loaded with glue between the board of the book and the hinge. Reload the needle with glue and come in from the other direction as well.
Smooth the hinge plate back into place. Place a sheet of waxed paper inside the front and back cover of the book to keep any excess glue from sticking to the book. Set something heavy on the book and let it set for a day or two.
Replace lost pages or text blocks in a slightly different manner. Open the book and lay it flat on a table. Run a bead of glue down the inside of the spine. Set the page or pages back into place. Put a piece of waxed paper on either side of the page. Fold the book shut and leave it for a day or two.