No, therapy cannot change sexual orientation because it is not a mental illness or a behavioral problem, it is an innate feeling that does not happen with learning or other factors that are subject to change. Because of the stigma in society many individuals who are homosexual or bisexual may seek therapy, or may be pushed into it against their will, to change their sexual orientation or make them straight, but the since there is nothing to change because nothing is wrong there, therapy does not work.