So just got my iMac back from the shop where I had to get a new drive installed. I have a time machine (a WD Passport for Mac). I turned it on and it look like a brand new computer. Plugged in my time machine, open settings and turned time machine on. Restart the computer while holding command and R and nothing happens; nothing. Does a normal start up and I do not get any pop up asking me to restore from time machine. When I start up holding the option button, I do get the option to select the drive or the time machine drive. I select the time machine drive, but it still does a normal start up from there and never gives me any option to restore. I know how to "enter time machine" but I don't know what I'm doing when I get in there. I need to restore the entire computer and would like to take it back to where it was the last time it was good. What am I missing or doing wrong? Thanks folks!!