I guess You cannot take the tablespace offline because it requires all the datafiles belongs to it available and online. But in this case If you try to take the tablespace offline, it gives you an error. So You have to take the individual datafiles offline. then you can start the database. But it is possible only when your database is in ARCHIVELOG mode to recover the datafile.
In your case two options are available depends on the mode the database was operating.
(1) If it was operating in ARCHIVELOG mode then you can still perform the complete recovery eventhough you do not have the backup of these tablespace If you have any complete backup (cold or hot) and you have all the archivelogs since that backup and till the time media failure happened, you can have complete recovery. elase perform incomplete recovery in which data loss is sure.
(2) IF your database was operating in NOARCHIVELOG mode, then I am sorry but yoy lost yur data. You have only one options which is RESTORE your last most recent cold bakup. and if you do not have anycold backup even, then you lost your whole database.
MS Computer Science
OCP DBA 9i/8i