If your NCO tells you to buy your plane ticket for leave, but your leave got denied after you bought your ticket, what can you do?

This is why you don't buy plane tickets until your leave is approved and plan out leave so that you have time to do it. I can't believe your NCO told you to go ahead and buy plane tickets before it was approved.

It depends on why the leave was denied and if others had leave denied too. I know we have certain time periods they tell people not to plan to take leave because of exercises we have going on. It's usually case by case basis during those times.

Talk to your leadership - work it up the chain.

Call the airline and explain it to them honestly. You may not get all of it back but it may be better than nothing. I don’t know if veteran organizations like the USO or American Red Cross can help but I’d give them a call if the airline won’t help. My service allows duty swap with others but leave maybe something entirely different. (Duty swap is when a buddy stands your duty and you stand his/her assigned duty at a later date. It’s usually used for members that need to attend a college class.) I’m not sure if that would work in the Army.

Not sure what angle you're taking on this. If you're wanting to keep the ticket and get your leave approved, you'll need to talk to your chain of command. If you're wanting money back for the ticket, well, that's between you and the airline and that depends on what they're willing to do. I'd definitely call them and play the military card. You never know, they may help you out.