The statistical yearbook (India 2012) is one stop place for a quick overview of the basic statistics in the country. You can find data on a wide variety of aspects of the Indian economy and society. Here’s a list of number of by strikes and lockouts in India since 1976:
To open spreadsheet in new window, click here
While industrial disputes appear to be generally falling post 1977, rising occasionally in 1983, 1986, 1996 and 1997, the sharpest decline was recorded during 1998-2002 when industrial disputes were cut into half. This coincides with the time when the judiciary was coming down heavy on political parties and labour unions for organizing ‘bandhs’ and ‘hartals’ (which from what I understand are different from strikes and lockouts). For more on the legal judgments, see: Bharat Kumar v State of Kerala (AIR 1997 Ker 291), Communist Party of India v Bharat Kumar (AIR 1998 SC 184) and T.K. Rangarajan v. Government of Tamil Nadu (AIR 2003 SC 3032).
Also – would you know where I can find information of the number of industrial disputes before 1977?