My phone is iphone unavailable and I don’t know my gmail password. Can I make a appointment to fix phone

Gmail has nothing to do with this.

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

How to reset your passcode without a computer if you have iOS 15.2 or higher.

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

How to reset your passcode using a computer.

If you forgot your iPhone passcode - Apple Support

Then, you will need to use the link that requires using a computer.

If you forgot your iPhone passcode - Apple Support