I'm not sure what happened, but this morning I brushed away a dust particle on my HP Pavilion laptop and the cursor arrow moved.
The touchpad hasn't worked in a month, since the last time I took it back to the store to get it fixed. And it would only work briefly between fixes before that. A couple months ago, I'd stopped using the touchpad and began using a mouse exclusively.
At the same time the touchpad started working this morning, my computer was acting kind of slow, as if Microsoft was in there somewhere applying a fix. Now it's working at normal speed again.
(For the record, the "two-finger scroll" function still doesn't work, but everything else does.)
I don't know what happened, but if it was a fix from Microsoft, consider this a notification that the fix worked.