Have a look for a fuse attached to the back of the light switch or the connections to it

Tony

This is the switch off of my 38. It doesn't have a fuse but I have seen some that do. You likely blew the master fuse on the ammeter. The car will still run with that fuse blown but nothing else electrical will work. As Tony recommends, check for a fuse on the light switch and also the main fuse on the ammeter. I believe the main fuse is a 30 amp but could be wrong. If it keeps blowing fuses you get the joyous job of tracking down a short.

On my 41 I replaced the headlight switch with a more modern one that had a breaker in it.  There is not visible difference on the dash. Saved me one morning when the lights went out while the sun was not up yet.  The breaker will reset and let the lights shine.  I was able to turn off the circuit causing the issue and have lights to get to where I was going.  When we rewired our 41 we broke out the circuits so they had different fuses to avoid the all or nothing issues.