Is sexual frigidity curable?

Yes it is. It's best to see your doctor for a good physical first to be sure there is nothing physically wrong with you. It's also important to know that diseases such as diabetes, heart problems, depression, adrenal gland and a dysfunctional thyroid (to name a few) can cause disinterest in sex. Even medications such as SSRIs that treat depression can cause a low to no libido. If your doctor tells you that there is nothing physically wrong with you then you would need to see a good sex therapist to help you come to terms with what is bothering you. Many people have sexual disorders and it's nothing to be ashamed of. Be careful about some sex therapists. Anyone that wants you to take your clothes off and perform any sexual act in their presence or have "group sex" is not the doctor for you! Believe it or not there are plenty of these places around.