B1 tax return

I came to Usa in October 1999 on B1 visa for six months. After working here for 5 months a consultant approched me with a job. He applied for my B1 extension and later applied for my H1 visa. He was not paying me enough and I also had to pay my hotel bills by myself. I was called back by my previous company. They also started paying me 2500 dollars per month although I as on B1 visa but applied for my H1 also. Since my B1 extension was applied so I was eligible to stay here till october 2000. I returned to India in September 2000. In the mean time I got the H1 visa approved by consultant. I came to USA on H1 visa from the consultant but i joined my previous company. Within a month I got my H1 visa from the present company also. I also filed my returns for the year 2001. Now I got this letter from the consultant saying that he received letter from the IRS for filing the tax for the year 1999 when I was on B1 visa. He said the letter says that I recived some money from the present company and they want u to file Tax forms. I was on B1 visa during that time. Do I still have to apply for my tax returns

It does not matter whatever your visa status was. You have to file a return and pay taxes if you earned income in the US, it is as simple as that!