my input jack nut fell off so i bought the fender replacement nut hex 3/8-32x3/32 TK NI. It was supposed to fit for my fender affinity strat but it was too small. So what sizes should i buy for a guaranteed. fithttp://imgur.com/wpMSg24

What it currently looks like without the nut.
Take it to a music store that has a guitar tech, see if they have one that fits in their spare parts bin. I've found loads of parts that way. Pickups, nuts, bridge saddles, tuners, tremolo arms, pick guards, knobs for vintage guitars or ones that got lost, grommets for the tuners on my 1966 Harmony, I can't remember what else...Most stores that work on guitars almost always have spare parts sitting around, but you never know it unless you ask.
Hmmm...I wonder what this button does...