First try these steps:
- Log out of your return
- Try one or more of the following:
- Don't use Internet Explorer.
- Clear cache and cookies,
- Sign in using a different browser.
- Sign in using a different device.
- Log back into your return.
If you really want to start over, you can click on clear and start over in the online version. See How do I clear and start over in TurboTax Online?