If you can not login to WordPress wp-admin page, rename folder Plugins.
After login you can rename it back to Plugins
How To Fix Broken Permalinks In WordPress
Are you getting 404 errors when you try to visit pages or posts through their normal links on your WordPress site?
This tutorial will show you how to fix broken permalinks in WordPress.
1. Reset Your Permalink Settings
Simply log into your WP Dashboard, then go to the permalinks settings. Change your settings away from the standard setting, for example to numeric, then save changes. Now simply select your standard setting again, and save the changes.
2. Check And Fix Problems With Your .htaccess File
If they don’t, set them to 644. Now go back to the permalink settings on your site and try to change the settings and save the changes once more.
Check your page again, still getting an error?
If you don’t, the easiest way to fix this, is to set the file permissions to 666, then reset the permalink settings, and then change your file permissions back to 644.