What to do if your iphone says unavailable

There is an Apple article that explains what to do if you have forgotten an iPhone or iPad passcode. Click on the following link: If you see an iPhone or iPad unavailable message or Security Lockout screen - Apple Support

If that option is not available, you will need to use a computer. See: If you forgot your iPhone passcode - Apple Support

I locked myself out of my iPhone

Reset / erase the phone, set it up again, and restore using a recent backup.

How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support

If that does not get things going, then you will need to use a computer.

If you forgot your iPhone passcode - Apple Support