First time I hear Zorin
Seems to be a Linux. I'm familiar with Debian based but I assume it is similar.
If you can not login in the graphical start screen after booting, you might not remember your password.
At the off chance that your login screen is borked, try pressing CRTL + ALT + F1 or F2 or F3 to get to a terminal. There, enter your username and password. If that doesn't work, you will have to boot a live usb and chroot to reset your password.
1) create a live usb stick (ubuntu should do)
2) boot it and mount your root disk
3) chroot to the root disk
4) use `passwd username`
5) close the chroot, umount the root disk, reboot
This should fix the issue.