In terminal type the following (be sure and type a space after rm)
rm “/Volumes/Macintosh HD/var/db/.applesetupdone.”
then type reboot
You will then be able to create a new user and then enable your existing account to be able to administer the computer. This works.
FYI, I found that the period at the end, before the closing quotation mark, has to be removed for this to work properly. Otherwise, I get file/directory not found error.