you're doing this wrong, you state what you have done, and as much info on what happened before it stopped working.
then people can start to help you figure out why it's not working and how to fix it
To uninstall minecraft correctly:
Push [Win]+R, type in %appdata%
Delete the .minecraft folder
Download minecraft from this page
https://minecraft.net/downloadReinstall
Reinstall Java:
Go to Add/Remove programs in control panel and uninstall it
Download Java from this pagehttp://java.com/en/
Reinstall
Next restart your computer and run minecraft through the normal launcher