Have you tried re-installing minecraft? if not, follow these steps...
1.) open the start menu and type in "run"
2.) open the program that is called run
3.) type in the program, "%appdata%"
4.) find your ".minecraft" folder, open it
5.) take these folders and copy them to your desktop: saves, resourcepacks
6.) now go to control panel and find minecraft
7.) click "uninstall"
8.) find the download for minecraft (or download it if you don't have it)
9.) run it
10.) when it is finished, then re-open (if you closed it) the ".minecraft" folder
11.) take the folders you copied to your desktop and move them back.
**If it asks you if you want to replace the files, click, "yes"**
12.) run minecraft. (If there is nothing in your start menu, run the "launcher.jar" in your ".minecraft" folder)

Tell me if there are any questions or problems.

Also, check if you have the latest java version installed.

Hope this helps!