which one is correct?
I can't help from noticing or but notice , and why?
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
***** NOT A TEACHER *****
(1) According to some experts, you could say:
(a) I cannot help noticing how beautiful you are.
(b) I cannot but notice how beautiful you are.
(c) This one is becoming popular, but some experts do not like it: I cannot help but notice how beautiful you are.
Source: Bryan A. Garner. A Dictionary of American Usage.
As the Parser has pointed out, two constructions exist: the most popular construction in conversation is can't help doing, while in more formal/literary parlance we still find cannot help but do, in which 'but' is a preposition (its original function in OE) governing the verb in the infinitive.