Maddie is right, read the letter and if there is a way to appeal you must follow the procedure, usually filling a form called "Motion to Reopen", is going to cost you a $590 more, this time start looking for more proof to bring next time(like letters of relatives, photos, witnesses notes, receipts etc).
you will receive a letter from uscis stating how long will take for them to study your motion to reopen.
If you think the USCIS made a mistake and you are paying the consequences you can fill a form claiming to the DHS ombudsman who is the watch dog over the USCIS.

