I had to leave US for being out of status. I was given 5 months, and since I had work violation (my hrs exceeding 20hrs+ in the college), I wasn;t allowed to apply for reinstatement. However I was able to finish my bachelor. and I left US exactly at the end of 5mth, which would help me avoid the 1hr ban thingy....

Now I was thinking of applying for Masters program. does anyone had any similar experience? would it be more difficult getting a visa again? what are my chances..academically i had a 3.5+ GPA (if it matters). Also I have a letter from human resources explaning the work violation was cause of their mistake. My DSO was a jerk and wans;t willing to issue to the I-20 required for the reinstatment purpose.

Any advices/suggestions would be appreciated.

There is no harm in giving it a try. I would suggest you get an I-20 from a better university.. better than the one from where you did your bachelors and also have a good reason for you to go back to nepal after bachelors other than work voilation.

All the Best

well, i am not sure how difficult it would be for you to come back.  I am not sure if your sevis no is in the database of US embassy in Nepal.  I am positive about few things here:

you went back after your undergrad which shows that you were not interested in remaining in usa being illegal

you have very good GPA, which shows that you were good student

Also, you have a letter from human resources and says that it was a mistake. 

I believe these things should work in your favor.  do not talk about you being out of status until and unless you are asked to clarify.  have your transcript and GRE ready and apply.  Assistantship will always helps. good luck.

It should not be a problem as long as you can convince people at visa interview. I have seen guys coming back into US after being deported ( caught while doing off campus job).