ORA-01113: file # needs media recovery ORA-01110
Found the answer: 

SQL&gt; recover datafile 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\EXAMPLE02.DBF';

alter database datafile 'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\EXAMPLE02.DBF';

alter  TABLESPACE EXAMPLE  drop datafile  'C:\ORACLE\PRODUCT\10.2.0\ORADATA\ORCL\EXAMPLE02.DBF' 


But for production DB it needs a lot of time to recover... Can't I drop that file without recovering it?

One more question... 
Another datafile was available during adding that file.. is there any chance that newly created datafile was used for storing data? I think oracle uses datafile until it will not exceed its maximum size and then switching to another available file... is not it so? 

I am asking this because I want to be sure that newly created file doesn't contain any necessary data...