Hello Dear,
It seems that your father is suffering from a psychatric issue.. it could be depression or something else..
Next Steps
there is a need to discuss his issues in detail to diagnose the problem and based on it treatment can be started.. you should take him to a psychatrist as soon as possible before the problem worsens
Health Tips
if he gets irritated , don't do same to him. understand that he has some illness , he needs your care, affection and love
don't advise him on changing things , it is not in his control
visit a psychatrist