if you are in OPT then you do not need a visitor visa, you should be able to get a new stamp to return to the u.s.
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Please see the response to your other question.
J Charles Ferrari Eng & Nishimura 213.622.2255 The statement above is general in nature, as not all the facts are known. You should retain an attorney to review all the facts specific to your case in order to receive advise specific to your case. The statement above does not create an attorney/client relationship.