I sometimes have quickparts and autotext disappear. No particular pattern that I can see. In most cases they were created some weeks/ months before hand.
Quickparts is sort of a catch-all phrase that doesn't have any real meaning. It is a heading that MS put on its ribbon to hold some disparate things.
I am assuming you mean Building Blocks. If you mean something else, please say so.
Building Blocks, including AutoText are stored in templates. When you create them you can specify the storage location. It has to be the Building Blocks template, the normal template, the template attached to the current document, or another loaded
Global Template. I generally keep my building blocks other than AutoText in a template(s) created for that purpose other than the Building Blocks template. AutoText is treated the same
except that if I want to use the AutoComplete feature of AutoText, I store it in the normal template.
Something else you may be talking about is AutoCorrect. The entries for that are stored elsewhere.
For building blocks I find Greg Maxey's Enhanced tools download helpful.