Major iTunes Problem

This is my first time posting in any "help" forum so please be patient. I have a very beginners knowledge of how to use my MacBook Pro. I only use it for iTunes and surfing the web occasionally. I hope not to be confusing with this seemingly long explanation of my problem but I am going to try not to leave out any details. I tried to update my iphone to the new software on Friday & I kept getting an error message about not being able to connect to the network, everything else was working fine. I did some research and saw a suggestion to delete and reinstall iTunes. I waited a few days, kept getting the same message, and decided to try that so I removed iTunes from the dock, into the trash. I have tried over a dozen times to DL iTunes again, every time I click "DOWNLOAD NOW", I am taken to the screen that says "Thank you for your DL" but not DL starts. I then did some more research and saw that I could just drag it back to the dock and so I did that. Once that was done my & I tried to open iTunes it said "iTunes cannot open because it may be damaged or incomplete." Itunes is no longer in my music folder. I decided then to log out & try my husband's user account, when I did that, iTunes in the dock had a ? on it and would not open. I then decided to put it back in the trash, empty the trash, and try the DL again. Still no luck same thing & now I cannot find iTunes in the finder, applications folder, or anywhere else. Please HELP!