The + sign on my iphone calendar is not highlighted so I cannot put new appointments on it.

Hello there, kmn53.

The following Knowledge Base article offers up some great recoomendations for when an application is not functioning as expected, that may prove useful in your situation:

iOS: Understanding multitasking

http://support.apple.com/kb/ht4211

If an app doesn't respond to your input, or doesn't perform as expected, do the following, testing after each step:

1. Check for app updates.
2. Force the app to close.
3. Restart your device.
4. Update your iOS device.

Learn more about troubleshooting apps.

Thanks for reaching out to Apple Support Communities.

Cheers,

Pedro.