When a blade breaks in a jigsaw, it can be difficult to figure out how to change it. This is due in part to the blade breaking off inside the blade guard housing. The trick is first to remove the remaining broken end from the housing. After you get the piece out, you can then insert the new blade into the slot, tighten everything up and be back at work in no time at all.
Unplug the jigsaw and lay it on its side on a worktable. Locate the blade screw. It is located just above where the blade should enter the saw.
Turn the blade screw counterclockwise using the screwdriver but don't take the screw completely out.
Hold the saw upright and tap on the side of the blade housing just above the blade screw until the broken off piece of blade falls out of the slot. If it remains stuck inside the slot, insert the tip of a sharp nail inside the slot to dislodge the piece. Continue tapping on the jigsaw until the piece falls out.
Insert the square end of the new blade into the slot. Jiggle and rock the blade until it bottoms out and the hole in the blade aligns with a small divot inside the slot. You will be able to feel it lock into place when the hole and the divot align with each other.
Tighten the blade screw using the screwdriver.