user not showing up on login screen but shows up in users and preferences

So,

There was originally one account on the laptop, I then added another account. I logged out of the original account and proceeded to log into the second account. Both accounts are admin. When I was going to log back into the first/original account, I wasn't able to find it, but the account is still on the laptop according to the settings. I've made a third account to try and delete the second account but I'm unable to do so. Im currently on the second account but wish to access the first account since it has all my files. Also when I first logged into the second account I was fiddling with the settings but Im not sure what I did to cause the first/ original account to disappear from the login. Please help because I didn't back up any of those old files and thats 5 years of files. Oh also I upgraded to OS X El Captian a couple of hours before I made another user.