Recovering Controlfile without Resetlogs

Oracle always requires you to recover and then open the database with resetlogs. However you do not always need to do a resetlogs when you open the database. If you recreate the controlfile rather than restoring a backup then Oracle allows you to open the database normally. Normally all information in controlfile like RMAN configuration and records, incarnation table etc will be lost so it is preferred to keep the old file.

Refer: http://www.articles.freemegazone.com/recovering-controlfile-without-resetlogs.php