I have a Pi3 application built in NODE JS which samples readings from 4 DS18B20 temperature sensors.
The sensors are connected using all three wires Data, Supply & Ground. I use a single 4.7k resistor to 'pull up' the data line to the 3.3V power line used to power the devices. Initially I used a permanent 3.3V pin on the Pi GPIO header to power the arrangement.
Sometimes I find that the sensors disappear and my application fails to log their temperatures. Restarting my NODEJS app or soft rebooting the Pi does not fix the problem. Only a power off restart of the Pi allows the sensors to the found once again.
So instead, I am now using a GPIO pin (3.3V) as the source of power for the four sensors. When my application detects the sensors have vanished I switch OFF the GPIO pin to power down the sensors for 20 seconds and then switch the GPIO pin back on. The sensors re-appear. A GPIO pin can supply enough current at 3.3V to power my four sensors.
So this mechanism seems to reset the 'hardware' side of the 1-wire bus and allows my sensors to be found once again.
I have not been able to figure out why the sensors vanish, but at least I can now recover gracefully from the problem under the control of my NODEJS app and without requiring a power off reboot of the Pi.
Hope you find this tip useful.