Recently I thought I'd lost all my calendar entries but it turned out to be easily fixed by adjusting an option in Settings. Unfortunately, I don't see a similar option in Settings for Notes. Thankfully I have not lost any of my Notes but I only have a few entries so far which sync with a Google account I have.
A Google search showed others were also having this issue but iPF won't let me post the link (not yet anyway). Basically, people just used Evernote instead which can optionally sync with Google's Notes as well.
Sent from my 32 GB iPad 2 using iPF