Originally posted by Calvin_Qiu
Try to drop objects located in those offline datafiles, then export all objects in tablespace mode.

Recreate the tablespace, then import objects.

or
Try to drop objects located in those offline datafiles
Switch database to archivelog mode
Recover offline databfiles and bring them online
Switch database back to noarchivelog mode
I doubt you can even drop the objects...

Regarding put in archive log, I dont see how that can help? You need ALL archived logs since datafile creation!