If you forgot the password to the Google Account that you used in your Google for Nonprofits request, you can reset the password here.
If you forgot which Google Account is linked to Google for Nonprofits, you can try searching your inboxes for the Google for Nonprofits confirmation email. It was sent from email@example.com.
If you're still not sure which account that you used, request administrative access to your organisation's Google for Nonprofits account. Your request will be processed in approximately 14 working days.