When i klick on itunes it says the itunes library

If you are on a mac first thing to do is close down itunes then go to your users folder then to the whoever is the current user folder and then the music folder and then the itunes folder. In this folder there will be the itunes library file single click on the file and then go the file menu and go to get info. under General if the file is locked uncheck this box and then close the "itunes library info" box

And then go to your applications folder then utilties and open up disk utility then click on your hard disk icon (usually the first one in the listing) then first aid will open up run repair disk permissions and it should correct the problem. This process could take sometime depending on the size of disk.

Hope this helps