I have a green card (based on asylum) and I am from Nepal. Can I visit only to India with my national passport for 20-30 days.

If you have a green card and the passport, you should be able to use it in India for purpose of US immigration laws. However, Indian laws might be different. Make sure you do not enter Nepal. Congratulations! If you entered legally, you can just go ahead and file for adjustment of status (Form I130 and I485 and other related forms) and you do not really have to leave while the case is in process. Within 90 days you will get a work permit. However, if you want to travel, you have to have an approved advance parole. The other way, is to just file an I130, then leave and wait for the processing to be done in UK. You might want to hire a lawyer to help. Good Luck Shah Peerally Founder and Managing Attorney of Shah Peerally Law Group PC Law Firm Deals in Immigration law, Bankruptcy & Debt Relief Note: The above answer is provided for informational use only. One should not act or refrain to act solely based on the information provided. No attorney client relationship is created unless a retainer is signed by the attorney and the client.