Another User Accessed my account and added a texture pack [duplicate]
Solution 1:
This was an update released with April Fools day, and is only available to 1.12 clients. You can read about it here: https://minecraft.net/en-us/article/try-new-minecraft-java-textures
Solution 2:
Texture packs are saved locally, it has nothing to do with your account. The different textures you're seeing are an April fools joke. See here (archive) for the announcement.