MrMediaMan, I'm sorry for your data loss! This isn't something OmniFocus does, so it's not something we can fix. It appears this is caused by a bug in the iPhone operating system, and can affect any iPhone application: so please report the issue to Apple so they can fix it.
That said, iTunes will back up the OmniFocus database when it backs up your other iPhone data; did you back up your phone after entering those tasks, and can you restore that backup to get them back?
Another approach you can use is to sync your data with a web server using the WebDAV protocol, so your data is safely stored outside of both the phone and iTunes. The easiest way to do this might be to sign up with Apple's
Mobile Me service, but you can also sign up with other (less expensive) services such as
BingoDisk or
bluehost.
But just because syncing is a possible safety net doesn't mean the iPhone should have lost your data in the first place! Please remember to report that issue to Apple, so they can work with you to figure out what happened and how to fix it.