I need to access my data but says iPhone unavailable

There is no way to access the data. Both of the following methods require erasing the phone but you can restore it from a backup later in the process.

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

Hopefully you followed this guidance before having it repaired→Get your iPhone, iPad, or iPod touch ready for service - Apple Support