I only see the "Other" account option on log in screen So i start up my macbook air after about 3 months of not using it, and i don't see any accounts on the log in screen, except for "Other," and I try to type in my old information, that doesn't work, and there's no option to create an account, so how can i create a new account?
Starting with 10.10 you can use the sysadminctl command to create users, assuming you're able to ssh in or something:

sudo sysadminctl -addUser username -fullName "User Name" -password - -admin