Why won't my minecraft open?

I recently downloaded Minecraft back onto my computer. I had used to play it without an account over a year ago but decided to buy it this time. I downloaded the.exe onto my computer and clicked it and all that happens is the waiting icon spins for about a second then stops and nothing opens. I used to play this game a lot and it worked every time. I also used to add mods to it and what not so I don't know if that has anything to do with it. I deleted the bin folder in appdata and clicked the.exe icon again and nothing happened. The program doesn't even run so i can download it or update it. It's not in my control panel to uninstall. Please help! I don't know what else to turn to. I'm running on a laptop using windows vista if that helps.