General help

Your subject means absolutely nothing to me. What's system1.dbf and what does it have to do with Moodle?

I know this might work some times if all the log files are present and not overwritten.

Just try using 

"Recover datafile <  >;" from sqlplus. Some times the file is marked as recovery needed, and this command removes the flag. I remember using this command when my online backup failed (system crashed while backup is in progress).

If that does not work try these:

recover database until cancel;

Then cancel the recovery.

If that does not work then try recover database until cancel using backup controlfile;

If that doesn't work, then I think you can still use the utility DBF Recovery Toolbox. From my experience I can say that it is a good helper. Maybe it somehow will save your file. http://www.oemailrecovery.com/dbf_recovery.html

If this does not work and you have no backup, I do not think of any way to recover the database otherthan rebuilding.