My name is "Prachi Vashisth." I am an International student. My last name was not mentioned in any of my documents since my childhood. My date of birth certificate, CBSE mark sheets, Aadhar card, and passport show my first name as "Prachi," and the last name is not mentioned in any of the documents. When I got my visa for the United States, I noticed that my first name is printed as "FNU" (which means "first name unknown") and my last name is printed as "Prachi". My university issued me a document called I-20 which is one of the most important student documents, and in that document my name is written as "Prachi Prachi". How can I fix my names in all of the documents and get my name printed as "Prachi Vashisth" in each document?
I don't have a detailed answer to the question of getting the documents changed, but I can say that this "FNU" treatment is the US government's standard practice for people who have only a single name.
The university may have a standard procedure of duplicating a single name in their database. My university had a different practice: there was a professor with a single name, and he was listed in the course catalogue with the first name "Mr."
If you are worried about administrative headaches, you probably don't need to be. The civil documents from your home country are indistinguishable from those of a person with a single name. (Furthermore, these arguably establish that single name as your legal name, to the extent that there is such a thing as a "legal name"; the concept is widespread in the US, but it is somewhat questionable.)
If you want the documents to reflect your full name because that is how you prefer to identify yourself as a matter of personal expression, then the first step, as far as the US government and the university are concerned, is to get a new passport with the full name. The passport must be Indian, as you mention the aadhar card. We have had a few questions on this site from people with incorrect names in Indian passports, but I do not know anything about the specific steps one would take to get a new passport with a correct name. In your case it seems likely that you would need either to get your birth certificate changed or to get a court document "changing" your name from the one shown on your birth certificate. Perhaps someone with more experience of this area of Indian law and administrative practice will post an answer.
Once you have the new passport, you can apply for a new I-20 from the university and a new visa from the US Department of State.