US Immigration from Ethiopia

If you overstayed abroad for more than 2 years, my parents stayed out for 26 months without a recently permit, can you be returned as inadmissible at the port of entry or denied boarding a us bound flight or will a judge have to see you in the USA before your permit could be revoked?

Has anyone did this? If so, did you experience any issues?

I looked at the guidelines on this site but I foolishly forgot to make copies of my i29f forms. So is it really needed for my fiancee to take to the interview. If not what documents are absolutely essential and which ones are not. I am aware the embassy will already have copies of it anyways.