Why do i have no power when i turn the key when my battery is good?

When did this problem happen, and maybe what sequence of events happened leading up to this problem. All I can suggest without hearing further is that maybe your battery terminals are badly corroded, or that the alternator is simply not connected to the battery. does the interior light work, the radio, the brake lamps, does every thing but the ignition work or does nothing work. If every thing but the ignition works, take a large wrench, find the starter underneath the truck, and slap the starter silly for a cuple of minutes. If it starts after that, drive it to the parts store and when you get there don't turn it off, for it may not restart, buy a starter while your there and possibly a soda (gets hot workin on cars), drive back home and replace the starter. If you need to, you can ask later on How do I replace starter or How do I drive back to parts store to get refund on core Ill gladly answere those too, with a little sarcasm of course.