A method and an apparatus to control a data storage system, and more particularly, a method and an apparatus to restore the stability of a head in a data storage system by automatically applying a bias shock current to the head in accordance with the result of a thermal asperity detection (TAD) method, in case that a quality problem occurs in the manufacturing process and/or under severe user conditions. A thermal asperity detection (TAD) routine operates if BER is large or an ECC error occurs in a process of manufacturing a data storage system or in a user field. Thus, it is determined whether the instability of a head causes a quality problem, and if it is determined that the instability of the head causes the quality problem, a bias shock current is automatically applied to the head to restore the stability of the head. It is accurately determined whether the head is unstable if the data quality problem occurs in the process of manufacturing the data storage system or in the user field to automatically restore the stability of the head. As a result, the quality of the data storage system is improved in the manufacturing process thereof and in the market.