If text messages were deleted off an iPhone 4s - can I retrieve them?

[xl]

Depends how you deleted them....
-did you empty the trash?
-is this webmail where you emails are moved to another folder?

[NFtoBC]

See the message "Transcripts" in this forum.

[JedWafu]

Try to check your iCloud Backup for the last saved messages.

[gadzxcv]

If you've made a backup in iTunes before, you can use an app to recover from iTunes backup file.