Was the rejection for a student visa?@Thash_91 Yes, In February 2017 for USA visa.
Since it’s recent I suggest getting help from an immigration lawyer.
My rejection was back in 2007 when I was a minor applied by parents for a visit visa. I was only 10 and I genuinely had no idea.
What I did was sending a mail to the us embassy and getting a copy of my rejection letter with the date as the rejection was not stamped on my passport and I did not have a copy of it. This took me 7 days. Attached this letter from the embassy and explained the situation that it happened 15 years ago when I was a minor and I genuinely had no recollection. I also took an affidavit which mentioned all the places I applied for a visa and the visa granted period and the rejection for USA signed by an attorney at law.