The DS-160 does clearly ask if you have ever been arrested at any time for any reason. If the charges were dismissed AND you did not admit to the elements of a crime, then you should not have been denied a visa for that reason.
If the issue is that they think you lied or misrepresented to try to hide it, then that is a permanent bar to any visa, but for a non-immigrant visa, you would need a 212(d)(3) waiver which has no form; it is just requested verbally at the visa interview.
It can be granted by the immigration officer at the interview or after on their computer (take a look at this link).