Legal Question in Employment Law in California

I assume that your employment contract is governed by California law, and that you are an at-will employee.

Under these assumptions, I see nothing unlawful in your employer's conduct. It does not appear that you have a promise from your employer to allow you to return to the US and take another position in the company if you are unhappy in India. While your employer may have replaced you "in retaliation" for expressing a desire to return to the US, that "retaliation" does not give you a claim against your employer.

You may have other facts that change this analysis. You may wish to contact a plaintiff-side labor lawyer directly to give you guidance. Many will speak to you over the telephone or by Skype, so that you do not have to come to the office for a consultation.

"Fair" has nothing to do with it and is not a legal requirement of employers. Unless you have a written employment contract specifying your 'rights' to return, you are probably at best an 'at will' employee under US law, if you are even covered by US law. Working in a foreign country generally places you under foreign law. I doubt there is much 'protection' of employees in India. Plus, you are 'quitting' by telling the company of your desire to leave your assigned job. Unless protected under your written employment agreement, you could be fired, even if you worked here in the US. I suggest you try to negotiate a reasonable solution, rather than thinking you can 'sue' later.