When you say all your profiles disappeared do you mean ALL or just the ones you expect to see? Does it say Matrix for the Profile down in the Camera Calibration section in Develop?
If they are truly all gone, then I’d say uninstall and reinstall the same version of LR, again. Did you update from LR 5.5 to LR 5.6, or did you upgrade from LR 4 to LR 5?
If there are some profiles but just not the one you want, or it says Embedded for the camera profile down on the Camera Calibration section, then you’re editing a non-raw file and the profiles should return when you are editing a raw file rather than a JPG or TIF or PSD.