I'm not sure what has happened but all of a sudden I am locked out of 1 of my stores. When trying to log in, another screen appears saying I need to "contact the store administrator for access "and to choose a different account. No one has access to my stores other than me and I can only access one of them. How do I fix this situation and has this ever happened to anyone else?
Please use the 'Forgot store?' option on the login page to have your account details sent to you.
Have you received any emails regarding access to your account? Please be sure to check in your email spam/junk folder as well in case any correspondence accidentally got routed there. If you have received an email from a member of the Shopify team, replying directly back to that email is the best course of action for further clarification and/or next step
In your case shopify support team is the only one that can bring your store back reach them to best possible way (live Chat)
Hope this helps!