Don't know where to go here

I have a toshiba satellite with windows 7 64-bit installed. It been giving me problems when opening iTunes or explorer saying its unexpectedly stopped working. I would like to just reinstall windows, I've done it before for a similar issue but don't remember what I did. I've tried different things I've found on google but I don't get the same screens as what's described. Can someone Walk me through this to get this figured out?

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