Turn signals not working

Today the turn signals at instrument panel stopped working. I checked exterior turn signals, also not working. Looked at interior lighting and found the ashtray lamp and glove box lamp not working either. Simultaneously, when I parked car, I turned engine off, but the ignition would not go into the "B" lock position so now I cannot remove my key. All this happened at same time. What could cause this? Where do I start?

My turn signals stopped blinking by themselves so I manually operated the turn/signal switch to make the lights blink. Then suddenly around two the three months later the turn lights are altogether inoperable. Tried checking the fuses and all seem ok. No breaks in any of the fuses. Also this seemed to happen after replacing one of my front headlights. Additionally after replacing that headlight my DRL is not working also.

The hazard lights are working fine, I should have included that in my question, sorry. Where do I go from here. Could a bad turn signal flasher make the turn signals completely inoperable?

Yes the flasher was the problem. It was located under the dash behind the cigarette lighter so a lot of disassembly of the lower dash panels was necessary. I have to give it to those guys at General Motors because first they didn't list where the flashers were in the owners manual or that it could even be the problem, and second every screw, bolt nut was a different type than the other making it no so easy for me to replace. And I have worked in the automotive service industry for about 15 years. So it came down to just a three dollar flasher. But I am back on the road now and am a happy camper.