problem renaming files

[Garry A. Leslie]

Being basically a lazy person I sometimes resort to importing files with numbers instead of titles, to save time.
I recently used the renaming files option in Windows to give some CDG files their correct titles, doing no more than deleting the numbers and typing in the titles and nothing else.
I can still find the files but they are now text files and not CDG files even though I didn't alter the CDG extensions.
I can't open these files, microstudio tells me they are deleted.
So could anyone tell me where they have gone or how to open them or do I need to import them all over again