My girlfriend starting to peed the bed again she 24 and don't know what to do i tell her she can wear a diaper for now until she fix the problem?

Loss of urine involuntarily (incontinence) is difficult and embarrassing. Have your girlfriend see a MD soon, either a Urologist or Gynecologist to assess for structural or neurologic causes.

She should see a Urologist and get urine examined too. In the meantime tell her to avoid tea, coffee, alcohol and reduce fluids in the evening, Once the cause is found and treated she should be OK