Will Turbotax Guarantee my refund due to lack of form 4684?

Your comments concerning someone preventing the IRS from paying federal tax refunds are specious and not based in reality.  TurboTax nor any other tax preparation software company can guarantee payment, nor pay a tax refund.

Do you need to complete a 4684 for Casualties and Thefts?  Were you affected by a federally declared natural disaster?  If so you need to complete the form 4684 -

To enter a Casualty or Theft loss using Form 4684 -

Click on Federal Taxes
Click on Deductions and Credits
Click on I'll choose what I work on (if shown)
Scroll down to Other Deductions and Credits
On Casualties and Thefts, click on the start or update button

Or enter casualty loss in the Search box located in the upper right of the program screen. Click on Jump to casualty loss