If you passed TET in 2012 and lost your hall ticket number, you should first contact the concerned TET board office where you appeared for the exam.

You can also check with your old school or exam center, as they may have records.

If available, use your name, date of birth, and year of exam while requesting details.

TET related information can be checked here:

https://competition.careers360.com/articles/tet-exams