When you graduate from high school or college, the diploma is one of the most rewarding pieces of sheepskin a young adult can receive. Besides the knowledge gained in four years of education, a diploma is something that can be framed, hung on the wall and cherished for years to come. In some instances, high schools, colleges and universities close down for various reasons. Degrees can get lost, destroyed or damaged, so if your school closes and you need a replacement diploma, it'll take some work, but a new diploma can be obtained.
Contact your state's Office of Degree Authorization or Student Assistance Commission. These departments might be one in the same, but they also might be two separate entities.
Locate the list of closed schools within your state and find the school you attended. In most cases, contact information is scarce, but the state organizations should have any information, like a school's new name or a website with contact information.
Contact your department of education if the school you attended that no longer exists has no contact information. The state DOE should hold records and can reproduce diplomas as needed.
Provide either entity, as listed in Step 2 and Step 3, with your graduation year, as well as your birth date and Social Security number. This will prove vital when looking up information from your years of attendance.
Warning
Be careful that you aren't contacting diploma mills or fake accrediting agencies in your search for that long-lost school you attended. The U.S. Department of Education has a great list of things to look for (linked in "Resources" section) and avoid when seeking your hard-earned diploma.