Position a large-sized shoe stretcher or shoe tree into the side of the shoe you want to stretch. Keep in mind that this would only work if the stretcher you are using is larger in size than the shoe itself. You can choose from a wide variety of shoe stretchers. For instance, there are stretchers which crank out to the desired size and those which are stationary and have to be forced into a shoe to be stretched.
Add half water and half rubbing alcohol to a clean spray bottle. Seal the bottle with the spray nozzle and then shake it vigorously to ensure a uniform mixture. To enhance the stretching effect of the solution, consider preparing a mixture of 3/4 alcohol and 1/4 water.
Liberally spray the mixture in the spray bottle onto the outside of the shoe. Be as thorough as possible and make sure that every seam on the shoe and the entire portion around the sole is sprayed. There is no need to worry about the effects of the solution on the shoe because it would not harm the shoe or the stretcher in any way. Spray the inside part of the shoe in a similar manner.
Set aside the shoes for about 4 hours, during this time the shoes will dry out. Try on the shoes after 4 hours to determine if they fit. If not, treat the shoes as before but use more alcohol-water mixture this time. Allow about 12 hours for the shoes to dry this time. When completely dry, try on the shoes one more time and check if you are comfortable wearing them. If not, your shoes are most probably a lost cause and would need to be replaced.