how do I reinstall windows defender for windows 10

It does not install. Error code 577

Please answer all four (4) questions by number:

1. Did the computer come with Win10 preinstalled or did you upgrade a Win7 computer or a Win8.1 computer [<=PICK ONE!] to Win10?
2. Has a Norton application or a McAfee application EVER been installed on the computer since you bought it?
3. Did a Norton free-trial or a McAfee free-trial [<=PICK ONE!] come preinstalled on the computer when you bought it? (Doesn't matter if you never used or Activated it.)
4. Have you ever run the Norton Removal Tool and/or the McAfee Consumer Products Removal Tool?

When in Control Panel I see the Icon for Windows Defender, when I click on it a message comes back reading Windows Defender has stopped working, If I have another program to protect me search for it in Services and Maintenance where the heck is Services and Maintenance located. It also said why it stopped working.

Dear Lucy et al,

It would appear, reading through all the 32 replies thus far: It might be Windows Defender thinks that you are being looked after by another anti virus app. or in your case a bad choice of finger stab. Because Defender is glued and nailed into the win 10 OS and does not function as a separate app might, the only way to clean it up and make it work is with a reinstall of Win 10.

This can be done automatically from the action centre found on the right hand side of the ribbon at the bottom of the screen. Hovering over each icon look for one that says something about notifications.

From there L click All settings>update and security>Recovery>Reset this PC.

It gives you the option of saving your old files.

Before you start all this do get rid of any third party antivirus program and back up your files to an external media, also clean up your Edge downloaded items and history too just in case they get carried over.  

Let us all know how it goes, good luck.

Hi,

To enable Windows Defender.

1. You may have to uninstall Avast to enable Windows Defender.
2. To uninstall Avast, follow the steps.

• Press Windows key + X and click on Control Panel.
• Under Programs, click on Uninstall a Program.
• Search and click on Avast. Then, select uninstall.

3. Once you have successfully uninstalled Avast, press Windows key and go to Settings > Update & Security > Windows Defender

4. Check (Switch ON) all the boxes. 

Hope this information helps. Please let us know if you need any other assistance with Windows in future. We will be happy to assist you.