Copy & Paste on MacBook Air laptop

I can no longer copay & paste as I did previously. Before I would highlight the item/article, hit the Command & C keys, then go to where I want to paste it and hit the Command & V keys. Now, after I have highlighted the item/article, when I hit the Command and C keys, I hear a popping noise and when I try to paste, by hitting the Command & V keys, nothing is pasted. I call Apple Support &, since I use MSN.com, they can't help me. I can continue to use this manner to copy and paste from my emails and/or google. I called MSN & they are only trained on microsoft products. I'm stuck ... HELP & thank you.