My VA psychiatrist Dr Hill determine that I was unable to work mentally or physically anymore he wrote me a letter I lost it and never turned it in

If you haven't worked 5 of the past 10 years, then you still may be eligible for SSI disability, also administered by SSA.  You would have to have very limited income and assets.  You should call the local SSA office to set up an appointment to file or consult with an attorney.  SSA will request your medical records, so you don't necessarily need to have the letter you are referring to.