I've looked all over the manuals and searched the forums but I can find nowhere the trick to getting the generator drive reconnected to my right engine that I inadvertently disconnected. Can anyone guide me to the solution? thanks in advance...

Go to the failures menu in the PMDG options, select active failures (which should be highlighted in red if there is any active failure items) and select "clear all" or the item you want to clear.

They should make some menu to allow us to reactivate generator by ground personnel.

That got'er done Matheus, thank you! Even while in flight too...

As in the simulation is a failure, it can be cleared always, in real world it needs the engine not running and a ground technician who will reconnect manually the IDG directly on the engine (so, airplane landed)

Yup, once this has happened in flight it cannot be reconnected until on the ground my maintenance staff.