Can't set my resolution to 1920 x 1080

So I recently downloaded WoW Wotlk and when i opened it the resolution was set to 1024x768. I tried to change it but when i click apply the game freezes for about 2 seconds and the resolution change doesn't save. Is there any way to fix it? I'm 100% sure that my screen supports 1080p resolution. I haven't tried reinstalling the game yet but I don't want to do that because i have slow internet but I'm willing to do that if it will help. (BTW other resolutions won't work either)