Around 1988, I worked for a company that refurbished electronics.
PC kit was so expensive then that I was paid to clean up keyboards, mostly from railway stations.
They'd stopped working because they were full of dust, dirt and general crap.
Easy job, actually. Photocopy the keyboard (really important!), pull all the keycaps off and drop into a bowl of hot water and fairy liquid, take the keyboard to bits, get all the plastic parts into the soapy water too, clean all the electronic bits up with isopropyl and a J-Cloth.
Make tea for everyone (including the MD).
Dry all the bits and put the keyboard back together. Do ten a week and it was really quite profitable.
I've never seen a keyboard as dirty as the OPs one.
You filthy disgusting person