Brief answer....although could be physical but mostly it is psychological in origin at such a young age.
Detailed answer....
Hello,
Thanks for the query.
I have read your query and understand your concern.
Although lack of libido and erectile dysfunction are different but the fact is both of them are interwoven.
There could be physical reasons or psychological reasons for your problem,although at such a young age as of yours,it is generally psychological only.
Physical reasons can include...
Heart problems
High blood pressure
Diabetes
Alcoholism
Drug abuse
Obesity
Lack of exercises
Anaemia,hypothyroidism etc
High cholesterol levels 
Lack of testosterone levels
Psychological reasons include..
Stress,anxiety,lack of time,extramarital affair,lack of sleep,social obligations,hectic schedules ,workload etc.
I would advise you to get tested for above mentioned physical causes and take medicines if any required  and do the following..
Do regular exercises.
Shed your weight
Stop tobacco
Moderate or quit alcohol for some time
Do yoga,deep breathing exercises and mental relaxation techniques.
Give 8 weeks to these lifestyle changes measures and see the effect.
In case you don't get benefit in these 8 weeks time,you must consult a psychiatrist for counselling and CBT ( cognitive behaviour therapy ) 
Stop watching porn as it leaves you in fantasy unreal world.
I hope it helps however you may revert to me for any further query.
Best of luck
Thanks

---