After giving resignation,1 month salary was in hold

Hello mam/sir I'm sivaraj,i joined a company 4 months ago,they gave a paper and asked to fill the details,I filled my education,skill and address and then at the end of the sheet there was a sentance,"i hereby declare that above information are true" and then they got the paper and I started working there for 4 months as an design engineer, I felt my job is a step back for my career,so I wished to resign and I asked the process of relieving with a important person in the company who worked there for 35 years,he said our company has so simple process,a relieving letter is enough,and I wrote a formal letter of resignation and gave it to my boss.he enquired the reasons and I answered him,he said okay and asked me to submit it to the receptionist,i submitted and asked the receptionist to give my salary,she said I'll inform you after asking the boss,after 8 days I haven't received salary, any calls/msg from the office,,i joined another company for a fair package and it's my farward step on career,on the 8th day I went there and asked why I haven't recieved salary,she showed me the paper I signed on the day of joining,at the back side of the paper there was a bond which I never saw,I never made ink to sign there,there was not even a column to sign,the bond says,I hereby declare that I work for 2 years in the company and if I failed to do, I'll pay my one month salary or work 2 more months till they get another labour to replace me and they said, "boss is asking you to work for 2 more months so that you can get your salary,",I said I never saw this bond and no one said about the bond,even on relieving no one said about this,I asked them you could informed me before so that I could continue the work for couple more months,but I have commitments now, I can't rejoin,they said "we lost your phone number so we were un able to reach you",I know it's a lie,I was going there daily on my lunch time and asking,they are not allowing me inside the security gate by saying boss is on leave",we will inform you after speaking with boss,..".I even tried to contact boss through phone,no one is giving his personal number saying that we will inform this to the boss. It's been 20 days, I was in so much mental pressure to manage a month without salary,still struggling. I don't know what to do next.please give me the procedures i should follow and the laws i should know for this problem.