I updated my Mac Book and have no access to my iPhoto files?

I assume that you just upgraded to Catalina.

Photos replaced iPhoto *years* ago. Photos can upgrade your iPhoto Library. Launch Photos with the option key held down. From the resulting dialog, choose your iPhoto Library. Photos will create a new Photos Library from your iPhoto media. Your iPhoto Library will not be changed.

Photos is not everyone's cup of tea. I happen to like it. Give it a chance to grow on you. There are other options.

iPhoto was discontinued 5 years ago. It is no longer developed or sold. It was replaced by the more powerful (and free) Photos.app that comes with the OS. You can migrate to that app very simply:

Hold down the option (or alt) key and launch Photos. From the resulting menu select 'Choose Library' and point at your iPhoto Library. It will do the rest.

If you prefer not to use Photos there are several 3rd party apps that you can use. Which to choose depends on the kind of photographer you are and your budget.