I accidentally my iPhone yesterday. What can be done now?
What do you mean? If you have deleted files on your iPhone by chance but created backups by using iTunes or iCloud, you can recover your files from these backups (https://support.apple.com/en-us/HT204184). If you have no backups, you can still try to use some tools like PhoneRescue or Dr. Fone for iOS to get back files you need from iPhone directly.