My skins folder isn't downloading everyone's skins

My skins folder isn't downloading everyone's skin like usual so unless I've seen their skin before they will have default skin. I think this is a bug with my folder. This started out of no where. No duplicates have had their skins file not download, I've tried to re download Minecraft and use past Minecraft data but it doesn't seem to work. Please Help. I've had past issues before on this but I have resolved those on my own, but I can't with this!