1. Currently at OPT (which expires on June 2009)

2. Applying for admission for Fall 2009 (which is Sept 2009). Suppose you got admission on March-April 2009.

3. Suppose new college issued I20 on April 2009. Here all your OPT/Visa all will be canceled and you will be in new F1 status. You will be in legal status as long as you maintain your F1 status and you don't have to apply for Visa if you don't leave the country.

4. Suppose you went to Nepal on April-May. You need to "APPLY FOR NEW VISA".

That is what I know. Please consult experts. Sajha is the place where people share their views and some share their experience.

Make sure you don't want to stuck and Nepal.