I'd like to know the difference between (1) and (2)?
(1) I had to do it.
(2) I have had to do it.
Happy New Year!
(1) I had to do it. - This is one complete action in the past. - simple past
(2) I have had to do it. - The means up until you "did it" any number of times. It could be just one time. The speaker is not specifying how many times he/she did it or when he/she did it. It could be any amount of times at any time up until now. This is why the present perfect is used here. - present perfect