When your client won't open, it is most clear that your problem involves your java. My suggestion is to reassure your java is updated to the latest version. You can do this by visiting https://java.com/download and looking at the download page. Next, Please restart your computer.
If your client launcher doesn't show anything at all when you run it, it could very well be that your computer isn't associating .jar files with Java.
This tool quickly fixes it for if you're using Windows: http://johann.loefflmann.net/downloads/jarfix.exe
If you run into any other issues, reply to topic.
Regards, Scape-War Team.