I want to make the trip to my website worthwhile for readers, so I'm including some samples of my writing. My question revolves around published short stories in general and one in particular. I'm curious who owns the rights to a short story where I wrote it and a publication accepted it, and then paid me and published it. In this particular instance, I'm pretty sure the magazine is now defunct. Is there a timeframe when rights revert back to me so I can publish on my website or did I sell all rights and I can never post it on my website since I no longer own the story?
There is no one answer for this. The answer is found in the contract for publication that you signed for the short story publication.
What you're looking for is the word "exclusive."
If the magazine licensed exclusive rights to publish this story electronically or in print or both, then they have the rights. Hopefully it's for a limited amount of time.
If it's not for a limited amount of time, then they still have the rights and you need to get them back. That's called a reversion.
If the contract said "non-exclusive" for electronic use, you're ok on your website.
If you did not sign a contract, and the magazine appears to be defunct, you send a letter saying you're reclaiming your rights. At least this way you've made an attempt to contact them.
In the actual real world, you're probably ok with publishing your own work on your website.
Things get a LOT trickier when you want to include anything previously published in a new book (like an anthology) with a company that's got some money and an insurance policy: their deeper pockets attract lawsuits.
The bottom line: as a writer, you must keep good records of where you've published your work and on what terms. This is not something you'll do "when you get around to it" because when I need to know if "Felix Buttonweezer Buys a Shi Tzu" has been published before, "I don't remember" isn't the answer I'm looking for.