Guys answer it plz !!!?

my guy and i were a perfect couple. buh it so happened that i totally threw my self onto him n dats where i went wrong ! still with the page of time , i ignored him ... he came back to his original state . now we recently have patched up. i need some advice that what should i do to keep him involved in me. he himself admitted that my sudden change and being introvert really changed him but how can i keep him thinking about me, not the whole day but to remember me as well as the rest of the activities. recently he asked my friend about my birth day. he forgot it ! thats y asked my friend :'( i felt so like rubbish ! plz help me out. i want him to notice positives in me. i am willing to change . just tell me how should i approach him n wat should i be doing to get him more into me???