My screen is cracked how do I fix it

Unless you see specific problems with the phone other than the broken screen, there's really no reason to think the drop has affected anything but the display. Do all the buttons work? Microphones, speakers and cameras all operating? Wifi, bluetooth and cellular data still fine?

So yeah, I'd try out as many functions of the phone as I could think of, but as I said, I wouldn't start by assuming there's more damage than just the screen. So let's get you going with how to replace the screen.

I wasn't able to find any step-by-step instructions like those featured on iFixit, but there is a YouTube video that looks like it will give you all the direction you need.

Oppo A77 5G/4G 2022 CPH2339 Tear Down/Disassembly & Screen Replacement - YouTube

You'll want to make sure you go through the video and check on what tools are used throughout the job first. You can purchase anything you need right here on iFixit if you want to support their repair efforts. A heat source is good to have; the iOpener works great, but you can easily get by with a hair dryer if need be.

Next, you'll need a replacement screen; those usually come either with or without the frame. The cost difference is fairly minimal and it's entirely up to you as to which one you want to get. My own opinion is that having the screen pre-mounted on the frame means there's one less thing I have to worry about gluing back down when I'm done with the repair. I usually start out looking on places like Amazon, eBay and AliExpress, but there will be many other places to get them as well. Find one that meets your needs with regard to price, delivery time, reviews, product quality and availability.

Finally you'll need some sheets of precut adhesive once you're done. Definitely want that for the rear cover, and probably should get some for the battery. Whether you need it for the screen depends on whether you get a screen with or without the frame.

Take lots of pictures as you do your repair and use those to create your own guide here on iFixit so others with the same problem will have a guide to go by! It's easy and fun and will help lots of people.

Create a new Guide - iFixit

Good luck; let us know how it goes and feel free to ask if you need help - that's what this site is all about!