Are you having a problem where your iPad keeps asking you for a password? If you haven't set up a passcode for your iPad and the prompt for the password contains your iTunes email address just above the input box for the password, it is prompting you to log into your iTunes account. This issue commonly occurs after an app download or update was interrupted, keeping the iPad from fully downloading the latest version of the app, and it is usually easy to solve.
First: Reboot the iPad.
This first troubleshooting step with most problems is to reboot the iPad. Not only can this solve the problem, but it will flush the memory and make sure we are working on a clean slate. You can reboot the iPad by holding down the Sleep/Wake button at the top of the iPad for several seconds. This will prompt you to slide a button to power down, and then you can simply hold down the same button to restart the iPad.
Look for 'Waiting' Apps
If the problem persists, the iPad will probably prompt you to log in as soon as you get back to the home screen. Our next step is to scroll through the pages and look inside of folders for an app with the word "Waiting" below it. This is an app that is caught in the middle of a download.
Once you find an app stuck on the download, you can safely log in to iTunes the next time you are prompted. This will finish the download and should solve the problem.
Note: You can log in to iTunes even if you don't spot an app stuck on a download. This will solve most problems, and it is usually just an app that you missed.
Open iBooks and Newsstand
Sometimes, it is a book or magazine causing the problem rather than an app. Simply launching iBooks and Newsstand will usually solve the problem, but just in case, you should scan through the contents to see if any item is stuck on "Waiting".
If you do spot a book or magazine stuck on a download, you can log into iTunes. This should clear up the problem.
Reset Your iTunes Store Login
In addition to a stuck download, the problem can also be caused by problems with your iTunes store login. To correct these, you'll simply need to log out of the iTunes store and log in again.
You can log out of your account by going into settings and choosing Store from the left-side menu. On the store page, simply touch where it says "Apple ID:" followed by your iTunes Account email address. This will give you the option to Sign Out. Once signed out, you can choose to sign back in and the problem should be solved.
Still Having Problems?
If the problem does persist, it may be time to take a more aggressive approach. Some issues cannot be solved through simple troubleshooting, but almost every problem except those caused by hardware issues can be solved by wiping your iPad and then restoring it from a backup.
Next, you will want to reset your iPad back to factory default.
Last, you will simply restore the iPad by setting it up just like you did when it was new. If you backed up the iPad to iCloud, you will be asked during the process if you want to restore from the backup. If you synced the iPad with iTunes, simply sync it again once you have finished the initialization process.