ok 2 diff scenarios here.
U press the TOGA switches, thrust levers advance automatically, u push them forward before THR HOLD annunciation, they will wind back, now, once THR HOLD (84 kts) announces the servos are inhibited and thrust can be manually repositioned. This is to prevent an A/T malfunction from retarding one or both levers during takeoff roll. Now some 17.5 seconds after takeoff this THR HOLD mode will change to ARM till u press N1 when they´ll go to CLB or if 150 seconds pass and you press FL CH.
Now if you press the TOGA switches and nothing happens with the thrust levers the A/T is probably inop. If you are dispatched with an inop A/T you still hit the TOGA switches because that gives you FD guidance and this causes the FMC to update its position to departure rwy.
Hope it helps...
Regards,
SW.