Recover datafile

1) check which tablespace is corrupted

SQL> select name, status from v$datafile where status not in ('ONLINE', 'SYSTEM');

2) take offline, recover datafile, bring it back online

SQL> alter datafile  'C:/ORACLEXE/ORADATA/XE/DATAFIEL_NAME.DBF' offline;
SQL> recover datafile 'C:/ORACLEXE/ORADATA/XE/DATAFIEL_NAME.DBF';
SQL> alter datafile  'C:/ORACLEXE/ORADATA/XE/DATAFIEL_NAME.DBF' online;