Accidents happen, especially if you have children, and one day the glass in your cabinet door may be a casualty. Whether it's broken, cracked or scratched, replacing it is usually a matter of chipping out some window putty or prying off a few pieces of wood trim. In either case, the door is easier to work on if you take it down and lay it flat. Be sure to wear protective gloves and eyewear to guard against shattering glass if your tools should slip or something else goes wrong.
Unscrew the hinges holding the door to the cabinet with a Phillips screwdriver and take the door down. Lay an old blanket on a flat surface, such as a workbench or table, and lay the door on the blanket.
Work out the putty around the edge of the glass pane you want to replace with a putty knife, if the pane is glazed, sliding the knife between the glass and the putty and forcing the putty upward.
Pry off the wood trim holding the glass with a slot screwdriver if the pane isn't glazed. Work the tip of the screwdriver between the trim and the wooden frame near a nail and gently pry the trim out until the head of the nail pops loose. Pull out the nail with a pair of pliers and put it in a safe place so you can reuse it. Continue pulling out nails until the trim is loose.
Put on leather gloves and pull out broken pieces of glass one-by-one. Or turn the door over and let the glass fall onto the blanket. Drop all the pieces of glass, or the entire pane if it is still in one piece, into a paper shopping bag and fold the bag closed. Thoroughly vacuum around the blanket and around the opening to remove small shards of glass.
Measure the dimensions of the opening with a tape measure and cut a new piece of glass to fit. Lay a piece of glass on the blanket, measure the width of the piece you need and make marks on either end of the glass.
Place a straightedge on the marks and score along the edge with a glass cutter. Hang the waste part of the glass over the edge of the table with the score line on the edge and, wearing leather gloves, grasp and sharply break the glass along the score line. In the same way, score and break the glass to the correct length.
Lay the door flat on the blanket and drop the glass into place in the opening. Replace the trim with the original nails by tapping them into the holes from which you removed them with a small hammer. If the window was glazed, spread new glazing around the perimeter with your fingers and flatten and smooth it with a putty knife.
Re-hang the door by screwing the hinges back into the cabinet frame with the original screws.
Before you repaint wooden trim, fill the nail holes with wood putty and lightly sand it when it dries. Window glazing may leave an oily residue on the glass that should come off with conventional window cleaner.
Consult your local waste authority for instructions on how to dispose of broken glass responsibly.