The perfect pair of jeans is hard to find, and once you find them you certainly don't want to have to retire them due to a lost button. A simple sewing kit includes a needle, thread in various colors and small scissors. A kit like this should be a standard fixture in every household junk drawer, and it is all you need to save your favorite pair of jeans from the tragic loss of a button.
Choose the button you want to stitch onto your jeans. If you are fortunate enough to have saved the original button after it had fallen off the jeans, use this one. If not, buttons are generally inexpensive and easy to find at your local craft store.
Cut a length of thread in your desired color to about 11 to 12 inches in length.
Pull the thread through a needle and pull the lengths so they are even. Tie a knot in the end of the thread to hold the length of thread in place.
Starting on the inside of the waistband, poke your needle through your jeans to where you want your button to be.
Situate your button in place on the outside of the waistband, allowing the needle to pass through one of the holes in the button.
Pull the needle through the next hole in the button and back through to the inside of the waistband.
Repeat this step as many times as necessary to secure the button into place, ending with your needle on the inside of the waistband.
Tie a double knot in the thread and cut off the excess.
If you want to wear your jeans and don't have time to make it to the store, consider cutting the button off of a pair of pants that you are not planning to wear. Just make sure it is roughly the same size so it fits in the buttonhole correctly.
A button that is too big for the buttonhole will not fit. A simple solution for this is to enlarge the size of the buttonhole with scissors and then secure the edges with stitching.