I am using macOS high Sierra. By mistake I converted my admin account to standard user account. Now by entering into the single user mode and trying to mount the disk,it shows message that "devise is write locked " and "IO failed , error = 13" and trying to remove the apple set up done file the error message is "no such file found." Please guide how to resolve this situation.
What were you doing when you "converted" the account type? There is no need to re-run the setup. Just toggle the checkbox in System Preferences > Users and Groups > Allow user to administer this computer.