Hey Everyone,
I’m new here and I know absolutely nothing! I have some .cue files and a .mds file and when I attempt to mount them (using Alcohol 120%) it says that the cd cannot be found. But why does the cd need to be found if I’m mounting the file? Doesn’t this create a virtual image so that the cd DOES NOT need to be found? This makes no sense! HELP MEEE! 
What it means is that there is no associated CD image file. A cue file generally requires a .bin file as the cue file only points to it’s associated data. It might also contain special information for burning the image. Similarly the mds file points to an mdf or iso file.
Sometimes the cue file can relate to an audio file or files, defining where the tracks are.
You can edit the cue files with Notepad & see what file is required.