Hi Noor. If I could invent anything, I'd do the standard infinite-food, infinite-water, and cancer-curing items to solve many of our biggest issues.
But on a more realistic scale, I think any sort of safe and affordable jetpack or other means to fly would be awesome. Not only would it make transportation a literal breeze, but it'd be loads of fun.
I've done a bit of research, and it sounds like we've already invented some prototypes for jetpacks, but they're still too clunky and expensive to really use.