I changed the oil and filter yesterday and while under the hood, noticed + battery post was a little corroded. I cleaned it and reattached wire to post now it won't start.

The battery is the first thing I would check.

The posts are good and clean and wiring properly attached. I remember the caps on the water cells being very loose and I've never messed with them in the 6 months that I've had the vehicle. My dad told me to try refilling them just up to the bottom of the cells with distilled water as he's had the very same issue before. That's my next step. After that, I'm going to try a new battery. I'd still like further suggestions from posters here though just in case.