one of my friend does not have social security number..... and he came here through student visa ,the visa is about to finish so what should he do to maintain the status . i have heard that he should keep on studying on that cause ....... is there any way where you can study here and go to Nepal for a vacation and come back .......

If you have a valid I-20 you can go back to Nepal and come back again with the same visa in your passport. If your visa is expired, take your I-20 and support documents to the US Embassy and apply for the visa.