I would like to know which of the taxes that I have paid while working on H2B visa would I be able to get back? I am from Bulgaria,but I think that it doesn't matter,actually,where I am from,because it should be all the same for all nationalities! I think I should get back my federal taxes?. but... is this the only one or..

It depends on a few factors such as how many days you've worked in US during the year, what is your status, do you have a family in US? Are you married? Do you have a child? etc.

Each case is different. Please consult tax expert.