We are aware of message migration issues related to the upgrade of TextMe apps. We apologize for the inconvenience and we thank you for your patience!
Please kill the app and restart it, that should fix the issue, and you should get your messages (not older than 60 days).
If not, please uninstall the app from your device and reinstall it again: http://tinyurl.com/textme-ios
You will not need to create a new account, simply log in with your same email address/username and password.