Yeah,a pic will help. If it's bent so bad it won't close,it's gonna take a little brute force to straighten.

 

to bend it back..
I have seen a guy back his truck into a semi dock to straighten his tailgate once, he had to remove the bumper prior and replace one of the posts after but it did straighten it and work great after he replaced the post.. I wouldn't personally recommend this method.. but yea.

might get a new tailgate shell instead, or just keep it lubed often.. eventually the parts will wear into the new angle and work better.

 

I realize that this is a year later but I finally got around to fixing my tailgate. The last few weeks it won't shut at all. I start by using chain cleaner and lube on all moving parts which only sort of worked. Then I took out the handle in the centre and lubed it up with synthetic motor oil since I happened to be changing my oil at the same time. I had to bend it a little so the arms would have less contact. Now it works like it's new. Thanks for all the tips.

 

Sweet. Thanks for coming back to this thread and letting us know

 

Never seen much about fixing a bent tailgate other than scour the junkyards for another one.