I have been playing minecraft on my current pc for many many hours.. but never got into mods or anything like that just played with too many items...... but lately my minecraft stopped working and i had to delete it... when i go to download it, it downloads fine and when i click the icon a window pops up to run it or cancel.. when i hit run the window closes and the cursor turns into the loading symbol but then goes away and nothing happens.. i have tried downloading all over again many times but it never changes... help please