Can’t log into my MacBook Air account

I can't log in to my MacBookAir account. I have the correct password. I read that after 3 attempts to log it should go to an option to change/reset the password, it doesn't do this.

I have tried to start up in MacOS Recovery by turning Mac on and Holding Command R and it just go straight to the log in menu.

I have another MacBook account and I can log into this one, of course all my files etc are on the other account. I do have an external hard drive which is backed up every day, but have read I can only use this on the account it is saved from.

Any help would be greatly appreciated. I am running a business and can't get into my files.

Thanks

Sharon