Submitting An Extended Abstract To Conference, But Later Changing The Methodology and Research Question Context: MSc student, first time having a paper accepted to a conference. 

I submitted an extended abstract to two conferences which were ultimately accepted. In the original extended abstract, I did not yet have results. The original extended abstract was also based on a particular methodology (optimization), but I ran into some computational complications solving my problem, so I had to change my methodology to 'simulation', and ultimately, my research question had to be adapted to the new methodology. 

So now I am in a position where my original extended abstract was accepted on the premise of the original methodology and research question, but now when I present at the conference I will have to present on a new question based on a different methodology. 

I feel like this 'bait-and-switch' is a bit of a slippery thing to do and my inexperience in publishing research and being involved with conferences probably influences that feeling, but my advisor said it isn't a big deal and now I find myself conflicted. From the perspective of my supervisor, they said that most conferences are understanding that research can change on the fly, which is why I should not be overly concerned that i'm presenting on something adjacent (but still very much related) to my original question and methodology. Additionally, the current title of my work is based on the original submission and uses a key-word in my field that signals to the readership that an 'optimization' methodology is going to be used (key word is "optimal"). 

I am wondering if I should reach out to the conference organizers and inform them of this change, particularly in regards to changing the title of the original paper. Or, perhaps this really isn't much of a big deal at all and this situation that I have described above is more common than I currently understand, in which case I can just leave it alone.
Depends strongly on the conference. It't not unusual (maybe 10% of papers) for presenters to present a paper on a substantially different topic than their accepted abstract at one of the most important conferences in my discipline. That's because it's considered a work in progress and discuss conference, so it's completely accepted that the question you thought about six months prior didn't actually work out.