Suggestion: If you install the
wonderful tagging utility MP3Tag, and you configure it to "recurse down through folders", you can then use it to produce one big list of all music files on your C-drive (or a complete list of any music file that supports a tag, anyway). So it will show everything except WAV files, as WAV does not support tags. By navigating it to your top-level C-drive itself, and with the "recurse subdirectories" option in effect, ALL music files located anywhere on your C-drive would be listed. Might take a little time to do the recursion through the entire drive, but you'll see everything when it's done.
In particular you WOULD CHECK the "subdirectories" option in MP3Tag's options (I normally have it un-checked for my normal program usage, but for your objective you would want to CHECK it):
Also, if you have additional hard drives you can just repeat this process on each one until you've got everything you want where you want it, so that you can do further work (maybe even use MP3Tag for editing your tags, renaming files, etc.!).
Note that once you've got the complete list of music files presented, you can further click on the column-headings, to sort the list into ascending/descending sequence by the values in that column. This might make it easier for you to then select/sub-select what exactly you want to move/copy to the new target folder location.
Furthermore, MP3Tag has a "filter" option (at the bottom of the window) so that you can further limit what is shown in that huge list of files, which again might make it easier for you to work with "groups" of music files at a time if that is to your advantage.
Also note that most of the data shown is from the internal tag fields or music file itself, although there is the external file name and full-qualified path shown as well. You can customize the columns shown by MP3Tag, both as to the actual columns shown as well as their presented left-to-right order. Just right-click on the column heading bar and select "customize columns...".
Anyway, once you've got the list of all of your music files showing, you then select them all (CTRL+a) or select just those that you want to select. Then right-click on the selected items and choose "COPY..." or "MOVE..." from the context menu, to trigger the dialog window allowing you to specify your target output folder to receive all of these files. Just navigate to where you want them to be placed, and OK. Bingo. Done. Might take some time depending on how many files you are copying/moving.
Try this on just a few files to learn with, and then apply the method to your whole set of music files.
Note that this is NOT a "copy to clipboard"... it is an actual COPY FILE (e.g. F5 keyboard shortcut) or MOVE FILE (F6 keyboard shortcut), hence why the "save as" dialog appears so that you can designate the target output folder.
NOTE: this will not delete any FOLDERS in which these music files live. It is only a way to copy/move all of your music files from wherever they might live on C, D, etc., to a single target output folder of your choosing (wherever that might be) so that you can then work on all the files in one single folder. But any further maintenance you want to do such as deleting the original myriad folders you might have, creating new folders for \Artist\Album collection organization, etc., that is a separate task.
EDIT: just noticed you are concerned with IMAGE files, not MUSIC files!!! I misread your original post.
Obviously my discussion above is for music files and MP3Tag, not for images. Sorry for the mistake (but I'll leave it here rather than delete it, because actually it IS a good method for doing the same thing for music files... if that was the mission).