I accidentally deleted all messages from my daughter. Can I retrieve them?

If you were using Messages in iCloud, then they are gone for good and there'd is niko way to retrieve them.

Use Messages in iCloud - Apple Support

If not, then you can restore your iPhone from a backup that has those messages.

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

Be aware that restore is an all or nothing process. You cannot restore only messages (for example) and any information between now and when the backup was created will be lost.