Hey there Unicornrodeo,
We understand your Memoji has disappeared after a recent update. We'd be happy to provide information to help you address this. First, you can just setup a Memoji again:
"Create your own Memoji
You can design your own personalized Memoji—choose skin tone, headwear, glasses, and more. You can create multiple Memoji for different moods.
1. In a conversation, tap 
, then tap 
.
2. Tap each feature and choose the options you want. As you add features to your Memoji, your character comes to life.
3. Tap Done to add the Memoji to your collection.
To edit, duplicate, or delete a Memoji, tap , tap the Memoji, then
tap 
."
And that is from here: Use Memoji in Messages on iPhone - Apple Support
Otherwise, check to see if you have a backup available from prior to them disappearing:
Locate backups of your iPhone, iPad, and iPod touch - Apple Support
Restore your iPhone, iPad, or iPod touch from a backup - Apple Support
Be aware when you restore a backup, it will erase what is currently on your iPhone, so you may want to make a current backup just in case you want to revert back: How to back up your iPhone, iPad, and iPod touch - Apple Support
Kind regards.
