Guild Wars 2

About three months ago I unlocked the 2,500 achievement points reward chest, shortly after I took a break from gw2. However after I returned I only had about 1,300 achievement points, but I do have the skin unlocked from the 1,500, and it also says I unlocked the 2,500 one. I somehow lost achievement points and I don’t know why or how, is there any way I could get them back? Could this be a bug maybe?

Edit: Added screenshot so you can see I unlocked the skin reward.

You get your first zenith weapon skin at 1000 points. You don’t get another until 2000 points, and then another (armor skin) at 3000, and so on. You only have one skin in your unlocked skins window. So, yeah.

Your screenshot only shows you have not yet unlocked the 2000 AP Chest, nor the 2500 AP Chest.

You may have been confused about your previous AP total, or I am missing something in the screenshots.