You must be having the appointment letter, and must have received the salary slips.
It is strange that you have never raised any protest.
Since you are Team leader in IT dept.,you have expertise in compters.
You may immediately collect your attendance records,and records which show that you have been entering office daily for work and leaving office daily after work.
You are an old employee therefore you may use your rapport and resources and obtain records from accounts or Hr which shall confirm your attendance was marked for each month of your service and salary shett was prepared.
You may collect all records of assignments handled by you, and reports submitted by you.
Other employees are being paid or not.
Once you have all the records with you, which shall establish that you have been employed but not paid,you may either file complaint with office of labour commissioner for concilliation proceedings or as adviced by learned Mr.Sheik Mohammed.
It shall be appropriate to show all records to your service lawyer/law firm before initiating your action.