Only add a zero to files and folders with a numerical prefix

[thedesignfactor]

We use a 3 digit file and folder naming structure such as:- 123 folder containing files like 123-1-123 filename.*** These main folders also contain files and sub-folders that do not have the 3 digit prefix - that start with letters.

We have now reached folder number 1000, and want to get them to sort correctly by adding a '0' prefix to all folders and files with an existing 3 digit prefix - to give us:- 0123 folder containing 0123-1-123 filename - leaving the ones that start with letters as they are - is there a way to do this?