Check the voltage regulator or let the engine crank a couple of turns and then see if the glow plug light and other lights come back on.

This is what happened on my other half's car,I let the engine turn slightly and then the lights came back on and the penny dropped that the only part that could affect it was the voltage regulator (I had a spare electrical part for the ignition to play with and this and the original both showed no dash lights during checks)

The engine turning obviously drives the alternators shaft so the regulator brushes then make better contact and the lights came back on,in my case one brush was completely worn and the other bad but making contact.