@ Stecal
I am trying to get information from as many sources as possible because i need to get the problem solved urgently. So i am not spamming, but trying to get information

This is a test database, so i was testing on it. I some how went for change database incarnation key. I think this might have caused the problem.

I have tried with the following command
SQL> CONN / AS SYSDBA
SQL> RECOVER DATABASE USING BACKUP CONTROLFILE UNTIL CANCEL ;

I was first asked about the following archive log file. So, i gave its location as:
N:\oracle\DEV\db\apps_st\data\Archives\DEVDFA6E9F5_00289_0673919223.001
Then, in a few minutes i was asked about the following archive log file:
N:\oracle\DEV\db\apps_st\data\Archives\DEVDFA6E9F5_00105_0673919223.002
After entering this file location, SQLPLUS got hanged. I waited for an hour but no response.

This happened with RMAN also earlier. The RMAN gets hanged while restore and recovery.
Why does the SQLPLUS or RMAN hang.

I am thinking of restoring the database with image copy (cold backup) that i had taken before this problem raised.

What could be the steps that i can follow to restore the cold backup keeping in mind that i have Oracle RAC 10 g with 2 instances on Windows 2003 server and running with Oracle Apps R12?

Detailed steps would be appreciated.

As it is test system, I dont care if i loose data, i just need to open the database so that i can carry on with testing.