I have lost the reverse lights on my 01 sport trac 4x4 auto trans. Any ideas?. on 2001 Ford Explorer Sport Trac

Just noted this problem last evening. All other lights OK

Asked by for the 2001 Ford Explorer Sport Trac
start by cking bulb and pwr at sockets if there is no pwr test rev switch
Thanks Greg, I have checked both of these (Bulb & power) I dont know where to locate the switch for the reverse lights?. Thanks JP