File object got deleted!

Hi

Today somebody deleted a PF from production, which holds the key to Invoice 
number, which stalled majority of Billing applications for 2 hours right in the 
Morning!!
I have 2 questions related to this:
1. Thinking that creating a new file from DDS will lead to recompiling all 
programs to avoid level check error, as a norm we can't compile with level 
check *NO) I requested the backup restore for which the AS400 operator took 
around 1hr45min. I wanted to restore the object in Production library so Format 
Level Identifier does not change, but he put it in my QPGMR libr. Creating a 
duplicate object, to production didn't change the Identifier??
I created the same object from DDS, the ID didn't change either...I wasted 2 
hours just like that?? (I already knew what data should be in the file.)
Can you explain me? Unless I change structure of file the format level id which 
has a reference in program object never gets changed? i.e. checking in the 
objects using implementer is good (lets forget the old data in the file for 
sometime)


2. How can we know from which AS400 id was this object deleted?. History log 
(DSPLOG QHST) is no good.

Thanks
Sachin