Minecraft 1.10.2 skins are not showing

I'm here because I was having a very similar problem. I've just managed to solve it, and I figured, even if this question is a bit old by now, maybe something I did will be helpful for you, or for whomever comes along next.

I was trying to mix and match some textures from my favorite resource packs. I found that, when I tried to modify the pack description in pack.mcmeta (the text after description:), even the tiniest bit - like deleting a character and then putting it back - Minecraft was immediately unable to recognize my resource pack. Here's what I did:

• I went to TextEdit > Preferences > Format, then selected Plain text rather than Rich text.
• While I was there, just for good measure, unchecked Add '.txt' extension to plain text files in the Open and Save options.
• And this took me forever to notice, but whenever I altered the pack description, the quotation marks around it auto-corrected to their slanted versions. Apparently, it's super important that they remain regular vertical quotation marks. When I finished editing my description, I just copied and pasted in vertical quotes before saving the file.

Some other info: I'm on OS-X Sierra, using Minecraft 1.10, pack format 2

If you're showing up as Alex, that means you've been randomly assigned the Alex model that's new in 1.9. Steve skins don't fit the Alex model, and it appears that accounts with the new Alex model have had their skins reset (maybe to avoid visual artifacts?).

To get your old skin and Steve model back, login to your profile on minecraft.net and change your model from Alex to Steve, then re-choose your skin with Choose File, and click Upload to re-upload your skin:

(As the profile page says, there may be a delay in seeing your skin update due to server caching.)