My IPhone works completely fine sometimes but a lot of times I can't use it and it's completely unresponsive to my touch?

I scheduled an appointment to fix my very cracked screen and I was just wondering if this will fix my problem for sure or is there something else that may be causeing the screen to be unresponsive?

Unless you go to the expense of taking it to an Apple store where they have the tools to perform an extensive pre-repair diagnostic test, you can't be sure.

But even they sometimes have to accept that you fix what's obviously broken first, and then deal with whatever that reveals next.

Sorry, but nobody here has access to your phone; all that's certain is that any touchscreen device with a broken screen is not usually going to work correctly with a broken screen. If you're unlucky then other parts got broken at the same time as the screen or failed afterwards due to the strain of trying to trying to compensate for the original fault.

The Apple Store appointment should help ID any issues & resolve them.