Lay out newspaper or a towel on the floor or table and set your picture frame down, backside up. With pliers or a similar tool, remove the backing and the nails or screws holding the picture and glass in.
Remove the picture from the frame. Brush the picture with your gloved hand or dusting brush to remove debris, including broken shards of glass. See if the broken glass has damaged the artwork. If it has, consider finding a new piece of art instead of re-framing this piece.
Pick up the frame and knock out broken glass from the lip, the edge around the frame that holds the artwork. Use the dust brush to remove excess glass or dust.
Measure for the size of non-glare glass you will need. Measure the artwork or the inside of the frame to find the size. Glass sizes come in inches -- or in feet for larger pieces. The frame's lip should be at least 1/4 inch wide, allowing some wiggle room for the glass. Don't cut the glass to the frame's exact size because it would not fit. Measure the inside lip of the frame and subtract 1/8 inch from the width and height.
Purchase the correct size glass from a store or online. Inexpensive non-glare glass may be non-glare on both sides, but higher quality non-glare glass has both a “shiny” and “matte” side. Before placing the glass in your frame, hold it up -- while wearing gloves -- and look at it straight on. If you can see yourself, that is the inside of the glass; if you cannot see yourself, that is the outside of the glass.
Lightly place the glass into the frame, frosted side down. Clean the glass using a non-static cloth and ammonia-free glass cleaner. Once the glass is dry, place the artwork atop the glass in the frame.
Partially lift the frame up from the floor or table and ensure that the artwork inside the frame is clean, the glass is in correctly and that everything else looks right.
Finish the back with staples, points, screws or tape. Replace the hanger and hang your artwork.