I accidentally factory reset my phone without backing up all my files. What can I do to retrieve all of them now?

Are you syncing Contact via iCloud? If so, then signing on to iCloud will restore your contacts. The last 30 days or 1000 Photo Stream photos will also be restored if you had Photo Stream turned on in iCloud.

As for the rest of the photos and data, you would need to restore them from a backup. When you set up the phone, you will be prompted to decide if you want to set it up as new or set it up from a backup. You can select your most recent iTunes or iCloud backup to restore from.

If you don't have a backup to restore from, then you have to set up the device as new. You can download past purchases, but aside from iCloud sync'd info, that is all you can retrieve.

Best of luck,

GB

Short of very expensive forensic recovery that is very expensive and not 100% recovery, there is nothing you can do without a backup. If you had iCloud backup on, even accidentally, you may be saved. It can't hurt to try this...

iCloud: Restore or set up your iOS device from iCloud