#1045 - Access denied for user 'root'@'localhost' (using password: NO)
Jessica, is this the full error message?
What exactly were you trying or doing when this error message appeared?
As much detail as possible helps with troubleshooting as we can't see your screen or know what you were doing when you get error messages or have issues with XAMPP.
Before you try and start MySQL using the XAMPP Control Panel make sure using the Windows Task Manager that there is no process mysqld.exe already running.
Did you set a password before to the many attempts at installing XAMPP?
What version of XAMPP did you finally end up installing?
(depending on your version there is resetroot.bat file in the mysql folder that may help, but in some versions it needs a tweak).