You may need to reset your phone. There is a glitch sometimes in Windows 10 where apps will disappear (I had it happen with groove a while ago) If you have texts set to sync and "apps+settings" set to back up, you can restore from a backup when you set up your phone. Make sure to give it a while to sync your texts, depending on how many you have it may take anywhere from a few minutes to a day or two to sync them all.