I can't login to my account on iTunes, but on App Store yes.

Hello Bar-trek,

If you have snow leopard (10.6.8) or older version of Mac os x installed on your Mac then open Finder and Go to User Account> Library > Preferences > and look for all items ending with itunes.plist and itunes helper.plist and then move that file to your desktop. And then try opening the iTunes and signing with your Apple Id if you are still not able to sign in then move those plist back to the preferences folder and if asked then replace the file in the folder as the new files get created when you open the iTunes .

For Os x Lion or later the Preferences folder in the user. Account is hidden, so to go to library click any where on your desktop and when you see " Go " option on the menubar at the top press and hold Option key on your keyboard and then click on Go and then Library and once you are in library follow the further process by going to Preferences folder as mentioned above.

If the above step does not work for you then you can try the below process :

Open iTunes by holding Option key this should ask you to create a new library ( you can rename this new library as iTunes test ) and then click create and once the iTunes is opened with New Library try to sign in with your Apple Id and see if it works and if still ot doesn't works then close iTunes and again press option key and open iTunes and you will be asked to create a new library or choose existing library and this time select choose existing library and select the library in the Folder Music > iTunes and if changing the library fixes the problem then the problem persist with your iTunes Library and you will have to Import all your iTunes data to the new library.

If still you are unable to login to your account using iTunes then try creating a new test user account with administrator privileges.

To create a new admin user account open System Preferences from the dock or by clicking on the Apple logo on top left side of your mac screen and then select system preferences and click on users and groups, click on the lock symbol and unlock it by entering your current administrator password and click on + sign to add a new account then enter name as test, keep password blank and choose account type administrator and click save. After the account os created click on lock in system preferences and log off from the current user account and then login to the new user account that we created with test name. Open iTunes and try to login and see if it works. If not then logout and then login back to your old user account and by going back to system preferences > users & groups> unlock and then click on test account and " - " to delete the test account and also choose delete all data and continue.

If still the problem remains then delete iTunes Application from Finder> Application> iTunes and move to trash and then empty the trash. And download the latest version of iTunes from http://www.apple.com/itunes/download and see if this fixes the problem and if not then reinstallation of Mac os x may be required.

You can Uninstall iTunes from your Mac by following one of the below method :

1> Remove iTunes 11

The easiest way to uninstall an App with all its associated files is to use the program App Zapper (www.appzapper.com).

App Zapper protects Apple products by default, so choose App Zapper > Preferences and untick the checkbox next to 'Keep Apple applications safe'.

Close iTunes and open the Applications folder. Now drag the iTunes 11 icon to App Zapper and click Zap. You will need to enter your password. App Zapper will show you all the files it is going to remove.

Note: The App Zapper application demonstration allows you five free 'App Zaps' so it'll probably be okay for this procedure.

2> Launch Terminal from the Utilities folder within Applications

Type the following commands:

cd /Applications/

(This brings you into the Applications directory), the next command deletes iTunes itself:

sudo rm -rf iTunes.app/

Enter the Administrator password to confirm

There is no warning or confirmation other than entering the admin password, iTunes will immediately be deleted, effectively uninstalling it from the Mac.

Deleting the iTunes application will not delete the iTunes library or music, and any purchases bought through iTunes will still remain tied to the Apple ID used to originally buy them.

( Do not enter wrong command, you can copy and paste the above command to avoid any mistakes )