Before trying to reset your password in case of login failure, please assure your device is set to correct date and time. A device with incorrect date set, will be perceived as an "untrusted" device, therefore login will fail.
If you have registered via the Quick registration process using only your email, your username is generated by the system. System automatically logs you into SAM from which you can at anytime convert your account to a full account from within SAM > MyAccount (accessible from Menu).
For password retrieval, you can visit http://slideme.org/user/password from your web browser or access this same link from SAM's Home Login/Registration page "Forgot password?" Enter your email address you used to initially register (either via Quick Registration or Normal-full registration. An email will be sent to your email address with a link, for you to reset your password to any password of choice. Always assure you make note if you used uppercase or lowercase characters in your password.
If you have not received an email to reset your password, check your spam mailbox. Otherwise it maybe that you entered an incorrect email or your email provider has not relayed the email to you. Assure you whitelist emails from SlideME.