Malware has highjacked my search function

[highmeadowhiker]

I followed the advice of a posting in another sectioni of this forum, and downloaded a "free download" suggestion. It turns out to have been malware. Now the search function of my browser has been stolen. Its logo is shown in the attachment. How do I get rid of it, and restore Google?

 

[Layback Bear]

Could you give us a hint what you downloaded and from where?
Can you give us the post you found this download in?