I had an ongoing conversation with an individual on my blackberry torch. I accidently deleted the running file which dated from 26 Nov 2010 to 8 December 2010. Is there a way to recover the deleted file?

Only way to recover it is from a backup file for your device. it might not all be there but if you backed it up in that time frame you can at least get something back. if not you can check deleted messages folder but that is highly unlikely with SMS.

I agree with Calebrity in that if you don't have a backup someplace, its gone.

Agreed, and your carrier does not store the messages anywhere after they were delivered.

use backup or instal program call undelete