I just purchased rocksmith 2014 for my PC during the set up phase after I calibrate my guitar the tuner will not show up on my screen and it keeps saying don't hit more than one string at a time (which I am not) and I cant go any further in the game. Please help

Is it a legit version purchased through Steam?  If so, try reinstalling, or verifying the integrity of the files.

 

To verify the integrity of the files:

 

 - Open Steam

 - Click on "Library"

 - Right-Click on Rocksmith 2014 and select "Properties"

 - Click on the "Local Files" tab

 - Click on "Verify Integrity of Game Cache"

 

That will force Steam to verify that all files relating to RS2014 downloaded and installed properly.

I purchased the game brand new from amazon (disk). I was able to get past the tuner last night only because it was already in tune the tuner never did show up on screen after that I  was able to pick a song and could hear the song and my guitar but the play screen would not show up on my computer 

I just done what you said and 1 file failed