Did you save a backup with Git or Dropbox or something? Why does an update delete your data anyway..?
Windows updates don't delete any data.
Well sometimes, if you had a strange file format that somehow depends on deprecated OS features? But yeah you're right, in general updates on any modern operating system should be trusthworthy
That's also a possibility, and even if it did "delete" all the files they would be stored in a folder called "Windows.old" on the main HDD.
