Everything needs to be fixed

@kellyfrederick well good thing there are a few guides out there for this. Here is the one for the rear glass Huawei P20 Rückabdeckung aus Glas tauschen and here for the LCD Huawei P20 LCD Display & Touchscreen tauschen Here is one for the speaker

For the buttons (not the power flex etc.) you may need to scour the auction sites like ebay.com to see if there are any out for sale. Of course aliexpress or amazon are another option. They are around, at places like this (example only not an endorsement).

We don't know where you reside, so for replacement parts do an online search and select a vendor that appeals to you.