so much wrong with this post...
a) use the code tags to format the code. Now it is an unreadable mess
b) scriptlets in your JSP. I don't even want to look at that mess. Learn how to combine servlets and JSPs to create clean, readable and maintainable code in which view logic and business logic are separated. The rule: no java code in your JSP, only tags and EL expressions (learn about JSTL).
So you get a blank screen. When you do "view source" in your browser, do you see anything there? If nothing, check if you are behind a proxy server. The solution to a post of not too long ago was that the blank screen was being caused by faulty proxy server settings (the user figured it out himself, I don't know what was done to solve it).
If all this fails you will have to do some debugging magic using your favorite IDE. It will probably be something stupid you are overlooking in the code. It is annoying, but debugging code that does not work is a big part of your job. Better get good at it.