In learning how to repair a cracked glass window, you won't have to master any new tools or esoteric construction techniques. If you can lay caulk or putty and handle a tape measure and putty knife, the damaged window pane can be replaced in the matter of a few minutes. Fixing the cracked glass window yourself will save you the cost of an expensive house call by your local glass repair company.
Remove the old glazing from around the window with a stiff putty knife. Heat the putty with a heat gun or in a pinch you can use a hair dryer. The heat should soften the putty and allow you to peel it off with the sharp edge of the putty knife. If this doesn't work, you can use a drill attachment called a putty chaser that has a flat blade like a blunt screwdriver and knocks away the old material.
Lay duct tape over the broken pieces and with gloves remove the broken window from the frame. Measure the inside of the frame, then have the hardware store cut a piece of glass to fit the inside of the frame.
Clean the frame. If it's made of wood, paint the inside of the frame with oil based primer so that the bare wood doesn't leach the oil out of the glazing compound.
Lay a thin bed of putty inside the window frame edges. Place the replacement window pane into the frame on top of the putty and press it down.
Knead more putty into a rope shape and lay it around the edges of the glass pane. With your fingers or the edge of a flexible putty knife, press the glazing compound into the angle between the lip of the window frame and the window pane.
Press glazier points into the frame in front of the window about six inches apart. Press the points into the frame with the blade of the stiff putty knife and push them against the window glass. This holds the glass in place while the window glaze is drying. Then, smooth the glazing putty over the glazier.
Dip the putty knife in paint thinner when spreading the putty over the outside of the glass to insure a smooth attractive and tight seal.
Wear gloves when handling glass. Wear eye and face protection when removing the broken pane.