It depends on the reasons. It is common to be denied a visa for lack of sustaining evidence or documentation. These are referred to as 214(b) refusals. To reapply, you must wait six months and be able to include more documents that prove your ties to your country of residence and/or prove significant changes to your situation in your next application.
Keep in mind: you will need to reapply and pay a new application fee. Please click here for full information on visa denials.