Did you sign up before September 2022? If yes, can you try the Sign in with BlockSurvey Wallet and use your Secret key?
Sign-in with email is a new feature that is available recently. Most likely, you would have used the BlockSurvey Wallet for sign-up.
Note: Check if you have the secret key from the previous account to log in. The secret is a file that gets downloaded to the machine at the time of Signup.