I doubt your gonna find an online manual for Compass detectors. What model is it and i'll see what I can come up with. There's a couple members on here that may have a manual or two for certain Compass models and I know of someone who may have one for sale depending on the model.
This is an Australian outfit that sells old manuals, or copies of them... I have no idea which model you need but here is what they offer for Compass...
COMPASS
INSTRUCTION BOOKS: Australian $ PRICE
Plus $ 2.00 Postage
Including GST
COIN MAGNUM 1 & 2 (Photocopy only) 3.80
MAGNUM RM 7 A / 420 / 320 / 220 Series (Photocopy only) 3.30
GOLD SCANNER & GOLD SCANNER PRO (Photocopy only) 2.00
Yukon Mineral / Metal Detector 1.50