i forgot my iPhone passcode , what do i do know ? i don't want to erase my phone

Unfortunately, you don't have a choice. Hopefully you made backups to restore from.

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 remove your iPhone, iPad, or iPod touch passcode without a computer - Apple Support

How to reset your passcode using a computer.

If you forgot your iPhone passcode - Apple Support

If your phone is disabled, you have no choice but to erase it and restore your most recent backup. See if this helps: If you forgot your iPhone passcode - Apple Support