If you’ve been developing custom WordPress themes for a while, chances are you’ve been in that situation where you login into admin, select your page to edit, then start banging your head against the LCD because you can’t find the Page Template dropdown to assign the awesome custom page template you just built. The front-end may even look fine, so what’s the deal? About 99% of the time I’ve had this problem all that I needed to do was reselect / reactivate my theme and voila! Especially after upgrades, I’ve learned this can be an invaluable step to ensure your theme is loaded properly.