Do you have an owner's manual? That would tell you what switches are where. Can you hear motors working when you hit the switch? If not check fusebox, and then try swapping a window switch out for the switch you think operates the headrests. The headrests are electric, and most of the switches in the car are simple mechanical rocker type switches and unless the pins are keyed differently they should interchange. If not and I'm totally wrong try to power them somehow with 12v at the plug end behind the switch to see if the motors and gear drives are functional. Should tell you whether it's the switch or the motor/mechanism.

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'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)