Restore screen on my iPhone

Maybe! If you ever plugged your phone into a computer that has iTunes or Apple Music there may be a local backup. It might not have all your data, but hopefully some of it!

Restore your iPhone, iPad, or iPod touch from a backup - Apple Support

Choose "Restore your device from a backup on your computer" in the article to see the steps for using a computer instead of iCloud.

There'll only be a local backup if he's made one, 'automatically back up my iPhone' isn't turned on by default (it should be) - and even if it was, a backup would only exist if he'd plugged his iPhone into his computer and clicked yes when the 'This iPhone hasn't been backed up in X weeks. Backup now?' message appears. If he'd done that, he'd surely know about it.

If none of the above is true, then there is no backup and his data is gone. Please stop giving people false hope.

Short answer: no

Long answer. nope.

(Where did you think you were going to find your data - just hanging around in the aether somewhere...?)

No, backup, no data. To avoid this happening again, get into a routine of backing up at least once every 2 weeks. You can backup either via iTunes (Windows) or the Finder or iTunes (if you're using macOS. Newer versions of macOS don't have iTunes (I forget when it was removed)). It is not advisable to backup to your computer's internal hard drive, for what I'd hope was an obvious reason (ie, if your computer's hard drive fails, you've lost all your backups), but to an external hard drive or flash drive.

Not possible. You're prompted to backup when you plug an iDevice into your computer (I plugged my iPad into my MBP this morning and was immediately prompted to backup). If there was a backup, he'd know about it.

You can try calling for sure since they might be able to better explain the procedure to you. Also there might be the possibility that you have an iCloud backup and don't know it. Unless you specifically turned that off iOS default settings usually have backup on automatically. They can help you see if you have one by walking you through how to check on your computer.

Sorry for the pedantry but, just as a FYI, 'data' is plural (the singular is 'datum'). It's Latin.