I bought application that doesn't work(crushes on start), can I get my money back?

You've tried deleting and re-downloading the app and tried contacting the developer (there should be a link to contact them on the app's description page in the store) ? If you don't get a reply from the developer then try the 'report a problem' link from your purchase history : log into your account on your computer's iTunes via Store > View My Account and you should then see a Purchase History section with a 'see all' link to the right of it ; click on that and you should see a list of your purchases ; find that app and use the 'Report a Problem' link (iTunes support should reply within, I think, 24 to 48 hours).

Some people have had a problem with the 'report a problem' link (it's been taking people to this site on a browser instead of showing a form in iTunes) - if it does that to you then try contacting iTunes support via this page : http://www.apple.com/support/itunes/contact/- click on Contact iTunes Store Support on the right-hand side of the page.