How do I Open a Folder in a new window?

Hi All,

Before I moved to my new macbook pro running 10.10.1, I was able to open a folder in a new window by double clicking (mouse or track pad). Now I do it. Double clicking does nothing. I checked my preferences and there was nothing in there for this. I check help and the finder file menu in the help did not match the actual finder file menu. The menu option and speed keys listed in the help file menu was not there and the speed keys did not work.

Any ideas?

Thanks in advance

Carolyn