F1 dropbox refusal

Hi.
I had a dropbox appointment scheduled at Chennai on 8th feb. I submitted required documents and case created on 12 feb as application received and case status remained same on dates 21 feb and 24 feb. But on 24 feb evening status changed to refused.
this is what was written on CEAC website
A U.S. consular officer has adjudicated and refused your visa application. Please follow any instructions provided by the consular officer. If you were informed by the consular officer that your case was refused for administrative processing, your case will remain refused while undergoing such processing. You will receive another adjudication once such processing is complete. Please be advised that the processing time varies and that you will be contacted if additional information is needed. For more information, please visit TRAVEL.STATE.GOV or the website for the Embassy or Consulate at which you made your visa application…
I have no information what happened and i want to know how to proceed further. Thanks

You should receive an email if 221g was issued.

I didnt receive any email till now.