Hi,
In the past I have used the CUETool to create a missing CUE file. You can download it here:
http://cue.tools/wiki/CUETools_Download
After downloading and importing, click the "Create CUE Sheet" action. For "Input" I find the "Drag n' drop mode" to be the easiest to use.
The files have to be part of an album based on their current metadata to work. You can find out all the info you need on that wiki site.
Dave