When we had our conservatory roof replaced last year, all the window keys disappeared. The fitters insisted they had not, and had no reason to have taken them out of the locks. Neither DH nor I could remember having taken them out and if we had, they would have been in the same place we always put them when we go away. We have found a key that does fit, but it is not the right key, though at least we can now lock the windows when we go away. None of the keys have turned up anywhere, and St Anthony has been singularly unhelpful (though he was very good when DD dropped her Fitbit when we were on holiday!).