You can use recovery mode to restore your iPhone or iPad if you've forgotten your passcode. To access the recovery mode, you need a computer and a cable to connect your iPhone to the computer. If ...

How to restore your iPhone with a computer In order to restore your iPhone, you’ll need to put it into recovery mode, starting by shutting down your iPhone.

If you backed up your iPhone, you can restore all of your information with your Apple ID -- this is your username and password you use to download from the App Store.