Google "CF card data recovery" and then comb through the results. You may have to try more than one option before finding one that works with your specific card.
A CF card has an IDE disk interface on the front end, so just like a hard drive, it has an onboard controller and different devices may not behave exactly the same when attempting a recovery operation. A USB converter or some other translator device can also complicate things, so if nothing else works, find a CF-to-ATA conversion dongle and try connecting it directly to an IDE port and see if it talks better that way.
Abacus Model 2.5 | Quad-Row FX with 256 Cherry Red Slider Beads | Applewood Frame | Water Cooling by Brita Filtration