1. Open a browser, click Tools → Manage Plugins, and disable all suspicious plugins, or you can know exactly what to keep. Then → Tools → Internet Options → General Page → Delete cookies→ Delete Files → Check Delete All Offline Content → OK → Set the used disk space to be less than 8MB (I use1MB myself) → OK → Clear the history → The number of days that the webpage is saved in the history: less than 3 → Apply OK (my own setting is 0 days).

2. Restore the default values of browser advanced settings: Tools → Internet Options → Advanced → Restore the default settings.

3. The method to restore the default browser "Tools" → Internet Options → Programs → There is a "Check whether Internet Explorer is the default browser" at the bottom. Check the previous tick and confirm.