You can check the status of your visa application at the Consular Electronic Application Center website.
Some visa applications require further administrative processing, which takes additional time after the visa applicant’s interview. Usually applicants are notified of additional administrative processing at the time of the interview. However, occasionally the need for administrative processing is not discovered until after the interview is completed. In these cases, the applicant will be notified by phone. Most administrative processing is resolved within 60 days of the visa interview, but the amount of time required will vary based on the individual circumstances of each case.
If your visa has been denied, you may find useful information on Ineligibilities and Waivers on the U.S. State Department web site.