Microsoft Office related files aren't opening by default?

So I'm sorry if the question is misleading, I wasnt sure how to ask this, but I have Microsoft Office 2010 I believe and for some reason I have tried almost everything I could for it to show in the Open with Default Program or whatever it's called and nothing seems to work. The only one in the Default Programs is Microsoft Outlook, but everything else such as Microsoft Powerpoint, OneNote, and Excel are still acting up on me. Microsoft Word so far has seem to also been working, but I looked around and simply can't find an answer that will solve this. I found some answers having to do with changing or fixing the Registry, but I dont wanna mess with that stuff since I know it's important. Anyone know of an easier solution? I have tried to go to a normal .xlsx file which should open with Microsoft Excel and I have been trying to change which program it opens with for the past hour or so and when i click Microsoft Excel and click OK it just kind of like ignores it and nothing happens. Please help T~T