Missing backup files

i use my WD Elements (wd15000EB035-01) as a Backup File only, but deleted some files by mistake.

How can I find the files I am missing?

The WD Elements does not perform automatic backups on its own without a dedicated backup application. Try verifying if the backup program you are using includes a file history or source comparison option.

Otherwise you may have to browse online for a dedicated data recovery program.