Try the following link as it has a few tips for regaining access. Could you please post the model number of your computer? Also assuming that you have Windows 10, usually the username is the same as your Microsoft account. In which case the page following has a recovery suggestion for that.
-Forum Member since 2016 -I do not work for Dell -A user helping other users -If you like an answer please click on thumbs up -If a reply is a solution to your problem please click on Accept as Solution Gaming on a home built ASUS B450-F Gaming with Ryzen 5 2600X Real work on an Inspiron 15 5575