Oracle Database Discussions

Hi i need some help on a test (but still important) database.

I am running Oracle 10.2 on aix. I had a datafile of which i have a daily copy of. However my datafile got deleted ( slight sub-question - when the file was deleted the database was up - i could still view and update tables that used the affected deleted file - how is this possible??)

I have tried renaming the copy of the file to the file that was deleted and starting up the database but that didnt work.

I then tried startup mount and recover database but i got the following error messages:

ORA-00283: recovery session canceled due to errors
ORA-00264: no recovery required

When i log into my database and try to view tables that used that file i can still see the columns but when i try to view the data i get the following errors:

ORA-00376: file 6 cannot be read at this time
ORA-01110: data file 6:

The file name is definetly correct - what am i doing wrong?

Many thanks