For flying if you pressed [R] While using nodus then that's a possible outcome or if you weren't standing on a solid block.

I don't use nodus! I don't even know what it is XD

Well then you were standing on a non-solid block.
like snow with no block underneath a glitched block ect.

I was on cobblestone I don't really care though as my dad made me get off the computer about 1 minute later XD

Ok that's weird XD.