Telling someone who doesn't have interest anymore to "find something something that interests you" doesn't work here, and is the most circular of arguments. It's like telling someone who doesn't have eyes "find something that can help you see."
I've been suffering from a death of interest/anhedonia for the past 2 years now following a psychotic episode. I can tell you that persistent anhedonia -- if it is not caused by medications, illicit drugs, clinical depression, or a recent traumatic event -- is incurable and is most likely a result of some permanent loss of brain functioning.
Anhedonia and lack of interest are two key negative symptoms of schizophrenia and other psychotic disorders.
"Loss of sex drive" can be caused both by medication as a side effect and the depressive aspect of bipolar itself so it depends. Ask your psychiatrist what is the cause of it. As for interests in life that you may have lost try to find something that interests and engages you as medication although neccessary is not going to solve everything. Although talk therapy and cognitive behavioral therapy can be helpful some active engagement in personal interests are good too and I've often found helped bring me out of a depressive state.