Usually you can boot into recovery mode by:
1.If your phone is on.Turn off you device.
2.Then, reboot by pressing the Power and Volume Up buttons at the same time .
3.Keep the buttons pressed for a short while – a few seconds – and then release the same.
4.The recovery mode menu should be displayed.
Samsung Galaxy S6, S5, S6 Edge, Note 5, Note Edge (and other Galaxy devices)
1.Hold down the Power key and select the Power off option.
If the screen is frozen or unresponsive, you can hold down the Power key for several seconds until the device switches off or pull the battery.
2.Press and hold the Power key, the Volume up key, and the Home button together.
Release when you see the Samsung logo. You can select the option you want from the menu using the Volume keys to highlight and the Power key to select.
HTC One M9, M8
The HTC One M9 is a little different:
1.Go to Settings
2.Battery and uncheck Fastboot.
3.Turn the device off by holding the Power key.
4.Press and hold the Volume down key and the Power key.
5.You should see a bootloader screen where you can use Volume down to highlight RECOVERY and then the Power key to select it.
OnePlus 2, OnePlus X
1.Hold down the Power button and select Power off to turn your OnePlus 2 off.
2.Press and hold the Power and Volume down buttons together.
3.You can use the Volume buttons to highlight an option and the Power key to select it.