Lost sexsual desires. Dont have any urge for sex. Why?

Doctor. It could be several reason from stress to depression. Talk to your doctor for evaluation and treatment.
Many Possibilities. Although there could be many possibilities, the most common reasons for loss of sexual interest are stress, anxiety, or depression. I would also consider new medications (side effects), hormones, and current relationship as possibilities as well. Talk with your partner or a medical professional for help.