If I was obliged to work from home, my most realistic earning option would be to continue to jump through the hoops required of my profession and offer private consultations in my house or remotely via Skype. If you're in the position of needing to make money, I think doing what you already know you're good at and capitalising on your track record is worth considering unless you're staying at home because you hate your line of work.
Otherwise, I would write. Fiction, trade journal articles, copy editing, advertising material, anything. I used to have a nice side gig writing a variety of professional material that I fell into by sheer good luck back in the days before everything was online (and, thank goodness, I had the sense to tuck some of the income into retirement savings), but I imagine it's much harder to make a living that way now.
And I wouldn't mind doing dog-walking and pet-sitting/short term dog-fostering, or taking in ironing and mending, if I was just looking for something to keep me off the internet and engaged with my community and to earn me some pocket money.