Lift the home button bracket starting from the left side.
Carefully pull it upwards toward the display, making sure not to damage the home button cable.
Scrape off as much of the old adhesive residue as you can, then clean it with acetone or high-concentration (90% or greater) isopropyl alcohol.
Secure the bracket with a high bond glue, superglue, or high-strength double-sided tape. Make sure the bracket is aligned correctly before allowing your adhesive to cure, or the home button will not click when pressed.