To be clear:
As jim said: the default Admin Password for the DEFAULT WORKGROUP is an empty string, but in order to have ULS "work" you MUST enter a non-blank password, otherwise you won't be able to log into your database - all users would be Admin, just as it is with the default workgroup file (which is system.mdw). If you're not using the default workgroup, then do you have a user in the Admins group? The Admins group always has permissions, and in general Access will require you to keep at least one member in the ADmins group (although you can, through code, remove that member). And, the creator of the db will always have the necessary permissions to open the db and manipulate permissions, so you could log in with that user.
If, however, you're using the default system.mdw workgroup as your workgroup file then you haven't enabled security at all, since all system.mdw files are identical, and thus anyone could open your database.
If you're not, then there's little we can do to assist you. EE guidelines are very clear in regards to circumventing security systems, and while you may be the legitimate owner of the database we have no way of knowing this.
