Can you restore iPhone without a computer?

No. But you probably have a friend with a computer or you can make an appointment at the nearest Apple Store for assistance. Or you can restore with backup as elcpu has outlined above..Instructions here...

If you forgot the passcode on your iPhone, or your iPhone is disabled - Apple Support

Yes, you can restore an iCloud backup. See below:

https://support.apple.com/en-us/HT204184