If it comes to shoes made of natural materials, primarily leather, do not despair. There is a solution for this problem!
In these cases you need to do the following
Take two plastic bags that can be sealed (with zip-lock). Fill 1/4 of the bags with water. Now put them in your shoes and then put your shoes in the freezer.
When the water is frozen, remove the shoes from the freezer. Now let them stay like that for about 20 minutes in order for the ice to melt. Then remove the bags and dry your shoes with hairdryer.
This trick is great for leather shoes and you should know that this method can spread your shoes up to whole shoe size.
This method can also be applied on shoes made from artificial leather. However you should note that after a while you will have to repeat the procedure.