External display no longer working

I recently purchased a Macbook Pro Retina 13" (Late 2013) model and was able to use it with my external display yesterday. Everything was working great out of the box and I was using the hdmi port on my mac to connect it to my monitor (dvi). Today though when I first turned on my mac after shutting it down for the night, my external display no longer receives a signal.
I've tested the cable and monitor with another laptop and everything is working, but for some reason just not with my mac.
I've tried resetting PRAM and SMC, and have been googling how to resolve this but have no luck. Any help would be appreciated.

So I somehow got it to work again, although it was unexpected, random and 100% luck.
I think what fixed it was that I switched off and unplugged the power strip that my monitor was connected to (I was reorganizing my cables). I didn't plug my rmbp right away though. The external monitor was still hooked up to my windows laptop. On a whim though I decided to plug the hdmi cable into my rmbp and it worked! My monitor set up also went back to how it was the other day.
I am sure that I didn't do anything on my rmbp that would have fixed it because I was just browsing internet on it. So if anyone is having this problem of where the monitor used to work but then suddenly didn't then I would suggest them to try this out. Let me know if anyone wants me to recall what I was actually doing. Good luck!
I think in the future to prevent this from happening again, I will probably unplug my rmbp from the monitor before shutting it down for the night.

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