Startup the database with the initialization file….
SQL> startup nomount
SQL> show parameter control (to check the path of control file)

Now create a control file

SQL> CREATE CONTROLFILE REUSE DATABASE “ORCL10G” RESETLOGS NOARCHIVELOG
MAXLOGFILES 16
MAXLOGMEMBERS 3
MAXDATAFILES 100
MAXINSTANCES 8
MAXLOGHISTORY 292
LOGFILE
GROUP 1 ‘L:\ORCL10G\LOG\REDO01.LOG’ SIZE 50M,
GROUP 2 ‘L:\ORCL10G\LOG\REDO02.LOG’ SIZE 50M,
GROUP 3 ‘L:\ORCL10G\LOG\REDO03.LOG’ SIZE 50M
DATAFILE
‘L:\ORCL10G\DATA\SYSTEM01.DBF’,
‘L:\ORCL10G\DATA\UNDOTBS01.DBF’,
‘L:\ORCL10G\DATA\SYSAUX01.DBF’,
‘L:\ORCL10G\DATA\USERS01.DBF’,
‘L:\ORCL10G\DATA\EXAMPLE01.DBF’,
‘L:\ORCL10G\DATA\UNDOTBS02.DBF’
CHARACTER SET WE8MSWIN1252;
NOTE: change as per your drive letter (For eg, if it shows K:, then change as K:\ and then write the same !)
Now try to mount ….
SQL> alter database mount;
SQL> alter database open resetlogs;

CAUTION:
a) Always multiplex the Control files and Redo log files.
b) Take a backup of the database.