how can i build my lost interest in studies, my lost intelligency, lost sharp mind, the attentiveness??? help.?

Im doing bcom hons..1st year..i scored 91% in 12th cbse...bt nw i dnt hv any interest in studies..nt even studies..my whole life has become dull type..i wake up late..no fear of college exam..no tension of my health..n i feel like im no more intelligent..like when i hv to sm work on studies..i dnt get ideas n my own creative thinking that i coud feel earlier bt not now..it feels like im getting degraded in all stuffs..like my mind dsnt work..im also been masturbating..is it only the main reason..bt i think its nt..plz help its about my life..n my own self i want to feel like earlier..the self confidence..the ideas..that intelligency...plz help..