If you are using Turbo Tax Online, the most likely reason for boxes/buttons that don't work or not being able to enter information is that something in the web browser is not displaying the page properly. There are directions in this TurboTax Help article to clear cache and cookies. You will want to follow those instructions, then close your browser, reload it, and log back into TurboTax.
Another way around this is to simply use a different web browser. You can select from Google Chrome, Mozilla Firefox, Internet Explorer or Safari. If you need to install another browser, be sure to go to the trusted home site for the software for security reasons.