ASUS X54L touchpad not working :(

Sounds to me like either the touchpad has failed, or the connection inside may have come loose. Without messing with it hands on, and seeing what you're actually looking at, I couldn't say for sure.

If it were me, I'd open the laptop up and check the wire connection to the touchpad, however I've been working on, assembling, repairing etc PCs since like 1995-6, when I was 13-14.

I'm assuming that if you had someone knowledgeable enough to ask for help, you would've also asked them this question, and that you likely wouldn't be asking this question if you were particularly skilled with doing PC repairs either. That leads to to assuming you are likely either going to have to have a local PC tech look at it, or live without having the touchpad. Laptops are somewhat complicated compared to a desktop, so unless you're extremely comfortable doing so, or at least extremely comfortable with the possibility of ruining the laptop, I highly advise against opening it up yourself.