Well if you didn't perform a full format of the memory card and didn't use it since then, you still have some chances. Connect the SD card directly in your computer through a card reader and run recovery apps such as Recuva or PhotoRec, you may be able to recover the file. If you're going to use Recuva, use Deep Scan mode...
If the .vcf was stored in the internal memory, then it's probably gone, but if you have root you could try some Android apps that do the same, but most of them are paid and aren't guaranteed to recover the deleted files...
Sony Xperia M dual [C2004]
ROM: 15.5.A.1.5 (stock)
Android version: 4.3 (rooted)
Bootloader: locked (unlockable)