Hi @Samantha Greenwood welcome to Atlassian community.
Please be informed, this issue frequently happens if you have two email addresses (e.g., a personal Gmail and a work email) or if you originally signed in using a social login (like Google or Apple) and then tried to log back in using a direct email/password combination, which created a new, blank account.
Few workable steps:
If you cannot figure out the original email or login method, you need to contact Atlassian Support.
It sounds like you might be logged into a different Trello account. Try logging out completely, then double-check the email or username you use to sign in. If you still can't find your boards, reaching out to Trello support could help recover your original account. @Samantha Greenwood If it helps kindly let me know.
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