Have a netflex account, but can not access with my kindle fire

You have to either hard reset the Kindle Fire and then sign in with the correct Amazon account it sounds like either the Kindle is set up with someone else's account or you not login to Amazon

To buy content and deliver it to your device, you will need to connect to a wireless network and register your Fire tablet to an Amazon account.
If you are setting up a new Fire tablet for the first time, you'll be taken through setup instructions and will have the chance to register your device. Follow the instructions on your screen.
To register your Fire tablet outside of the initial setup screens:

1. From Home, swipe down from the top of the screen and then tap Settings.
2. Tap My Account.
3. Tap Register.
   • If you already have an Amazon account: Enter your Amazon account information, and then tap Continue.
   • If you do not have an Amazon account: Tap Start Here, and then follow the instructions to set up a new account.

Note: If you've forgotten your Amazon account password, you can reset it by requesting that a personalized "password reset" link be sent to your e-mail address. To learn more, go to Reset Your Account Password .
If you need to deregister your device from an Amazon account, follow the steps above, and then tap Deregister. After you deregister your device from an Amazon account, you won't be able to access items stored in the Cloud for that account.
After deregistering, you can register your Fire tablet to another Amazon account. Related Help Topics

• About Wireless Display Methods for Amazon Devices

Carole, Yes, some one else could log into there account, if your account is logged out. Check the attached links,instruction and guides, Good luck
"I hope this helped you out, if so let me know by pressing the helpful button. Check out some of my other posts if you need more tips and info."

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All you need to know is the e-mail address you used to open your Amazon account and your password. If you can't access your Amazon account give them a call and they should be able to help. You can always open a new account if there isn't a good reason to connect to your old on e.g. prime or pre existing kindle library.

You would need to deregister the device from the new email address/account and register it to your old address/account, the one that has the rest of your books.

Once registered to your previous account you will be able to take advantage of the Kindle Owner's Lending Library feature.
Here's more information on it: http://www.amazon.com/gp/help/customer/display.html?nodeId=200757120


Once you've registered your Kindle to your own Amazon account you may still be able to access any books on your previous account if you can take advantage of the Family Library option. Information here:

http://www.amazon.com/gp/help/customer/display.html/ref=help_search_1-1?ie=UTF8&nodeId=201630380&qid=1425455853&sr=1-1

You will need to download the Kindle app ( from the App Store ) on your iPad or iPhone. You can then access your account on Amazon and probably download whatever you have on the Kindle to those devices. I have it and it works great....never went back to the Fire.

Note: Your Kindle Fire lock screen password or PIN is different from your Amazon account password.
Reset Your Kindle Fire Reset your Kindle Fire if you forgot your lock screen PIN or your parental controls password and need to regain access.

If you have any content not saved in your Kindle Library in the Cloud, be sure to transfer that content from your device to your computer via USB.

Important: Resetting your Kindle Fire will remove all content downloaded to it. Any content you purchased from Amazon is saved to your Kindle Library in the Cloud and will remain in the Cloud. You can download that content again if you register your Kindle Fire to your account again.

1. From Home, swipe down from the top of the screen, and then tap More.
2. Tap Device.
3. Tap Reset to Factory Defaults, and then tap Erase Everything.

Your Kindle Fire will restart.

To use your Kindle Fire again, you'll need to connect wirelessly and register your Kindle Fire.

Log onto Amazon Kindle account. Go to Help desk and send them an email. They can email an answer or call you about it.

https://www.amazon.com/gp/help/customer/forums/kindleqna?cdForum=Fx1GLDPZMNR1X53&cdThread=TxO03X0THSPF9Z