I turned the wrong way in deep forest. How to get back with safe?

If you have enough signal to post this then you have enough signal to download a compass and map app

If you're serious then STOP. Don't start walking randomly.
You've got a phone. You can determine where you are.
DO NOT wander around.
Where you are now is your home base. Identify it. Once you get your coordinates walk in as straight a line as you can. If you feel you're going the wrong go [i]right[/i] back to where you were and try again.

climb a tree to get a vantage point
follow the sun or keep the sun behind you keep going