My name is Ananya and I work for the Social Media and Community Team at Dell. I regret to hear about the issue you are facing. The first step you can try is boot into safemode and check if the user name is listed out there . Please try the following steps.
Step 1 - Once you turn on the system tap F8 at dell logo
Step 2 - It will take you to Windows advanced boot options
Step 3 - Using down arrow keys select "Safe mode with Networking "
Step 4 - once it shows you the user names list see if that username is listed out there , If yes select the user name and login
Glad to assist you!
Thanks and regards
Dell Social Media Responder