Multia1,
I'm with safetypee and Jonty on this one. The first thing I would do is confirm that the engine is in fact failed/stopped by checking the engines other parameters (EGT, EPR, fuel flow/pressure, oil pressure/quantity, hydraulic pressure, electrics etc) and compare with other operating engine/s, then slowly retard the thrust lever to idle and monitor that engines parameters and see if they follow the thrust lever movement back to idle readings. Then, if in fact they do follow thrust lever movement, I would slowly advance the thrust lever and see if they follow thrust lever movement back up to match the other engine/s parameters. At least if the suspect engine's other parameters follow thrust lever movement, (without vibration/fire warnings) you would more than likely have an inoperable N1/N2 indication.
Rgds McHale.