i am trying to unlock my iPhone using a library computer as I'm out of town and have iPad only with me

If the Library computer has iTunes installed and a free USB port see here: link-> If you forgot your iPhone passcode or your iPhone is disabled- Apple Support

Otherwise, you may be able to use iCloud.com to wipe the iPhone and set it up again: click here-> Erase a device in Find My iPhone on iCloud.com - Apple Support

From:

If you forgot your iPhone passcode - Apple Support

"If you're using a PC, make sure that is has Windows 8 or later, and that iTunes is installed." Chances are a library computer will not allow you to install iTunes. All I can suggest is to try the Genius Bar in an Apple Store near you if you don't have access to any other computer.