Lighters are wrongfully thrown away daily. Reading this article will save you money.
When a lighter want fire up, verify it is not out of butane. If it's not out of fuel, put the lighter in your other hand and see if it works. This will cause pressure applied to the flint wheel to be at a different angle.
Another cause for a lighter not to work, is trying to fire it up with lotion or oil on your hands. If you are guilty of this, the lighter will probably fire up, after you've let it alone for an hour or more. In some cases you may need to rinse the oil from the lighter with alcohol. (If you've chosen to rinse it with alcohol, you'll have to give it time to dry).
The thrifty can save a lighter that won't fire up if the flint still works. When you have another lighter that has butane but the flint wheel doesn't function. In a push you can light the fueled lighter with the other lighter. (Tilt the lighter, you're trying to light, at a 45 degree angle for best results).
A lighter that has been set aside for a while and has accumulated rust, sometimes can be revived. You can just carry it around in a pocket or purse for a day or two and the rust frozen flint wheel may break loose and spin again. Another way to break a flint wheel loose, is to spray or splash the lighter with vinegar. A few hours later spin the flint wheel and the lighter may work again.