My computer is asking me for the product key? its unreadable.?

so a couple of months ago my Computer got wet and i took it to go get repaired since it stopped working now that ive got it back(had it for some months now)its asking for the product key but since it got wet and with regular wear and tear i cant see the product key. i have a toshiba satellite l305d-s5881 or had i dont know what they hade to repair