I took out the E key on my keyboard to clean the dust out and when I put it back in, the touchpad had stopped working completely. The cursor wouldn't move and the buttons wouldn't work. I restarted the computer, but that didn't fix the problem. In fact that only made the cursor disappear altogether. I tried doing a system restore but that didn't help, I took the laptop apart to make sure the touchpad was physically connected and that the ribbon didn't slip out of place or anything like that which it didn't, I went into the settings and it said the touchpad was enabled and working correctly and that the drivers were up to date. So with that, I'm stuck. Anyone have any ideas? If I plug an external mouse in, that works, but the touchpad doesn't.
Does an external mouse work fine? If so, then I would say it is hardware. Even though you say the connection was not knocked loose, you stil may want to try disconnecting and reconnecting it. All it takes is a tiny bit of movement and then it won't work.