Just find out the denial reason and consider reapplying or filing an appeal.

 After being found ineligible for a visa, you may reapply in the future, If you reapply for a visa after being found ineligible, with the exception of 221(g) refusals, you must submit a new visa application and pay the visa application fee again

If your visiting visa application to the United States (such as a B-1/B-2) was denied, there is no time limit before reapplying

You can reapply or just ask why it was denied