Help!! Undo tablespace gone!!

I restored the database from Backup Exec and when I tried to recover I noticed that there is no Undo tablespace among the restored ones. I have no other backup of the table. I tried to change the init file as not to use the undo tablespace at startup, still cannot recover. Please help, is the production db!!

Try and restore if you have a valid

else

open TAR to support , they have a bad of tricks available that may be able to open it, you'll hav to rebuild afterwards but at least you might be able to open it