I have 5 years B1B2 multiple visa and i entered here on May 22 2011 but the immigaration inspector grant me only for 1 month in the airport which is going to expire on 20 May 2011 What should i do in this condition in order to extend my stay in US? Which is the best way for me ? what will happen if i get back to nepal and come again after some time. Pl give the best advice.If some body give me the best advice would be highly appreciated.

I am telling you what I know, you will have to research further but hope this helps.

Your VISA will allow you to come back to US if you leave after a month, until 5 years. Do not plan to overstay beyond the 1 month period. If you must stay beyond the 1 month period, file for an extension with the USCIS. It could take almost a month sometimes to hear back so file the extension quickly and be prepared to leave if your extension is not granted OR you don't get the response before your 1 month expires.