Minecraft worlds do not save

About a week ago, my worlds stopped saving when I exit on single player.

I tried a lot of ideas and looked around the Internet. I then deleted the .minecraft folder and the Minecraft launcher. I re-downloaded Minecraft and the worlds were saving on exit.

I made several worlds and all continued to save on exit. I then resumed using my regular texture pack and the worlds stopped saving.

I am suspicious that my texture pack is the source of this problem.

I saw another question and the person also downloaded a new texture pack. The thing is I've been using this texture pack since 1.8.0 and never encountered this problem. I have modified it a little, but I don't think this is the problem.

Is my texture pack broken or corrupted?

And if so, can and how can I fix it?

Update:

I got a new .minecraft folder, made a world and saved it. It saved and all was good. I then downloaded and installed optifine 1.10.2 for the new .minecraft folder. It stopped saving the worlds. I logged in and out many times and at first it was saving but gradually it stopped saving.

I don't know whether my texture pack was causing the problem because this time I used only optifine with no texture pack.