>my computer have some virus and now can't open and download java
Try and get rid of the virus first (if you're sure that's what is causing the problem) before making the decision to reboot your operating system. If you need help post in the technical section on this forum and I'll try and help you out (I'm no computer wiz but I know my way around and have plenty of experience using virus scanners/registry editors/methods to get rid of viruses, spyware and other malware). ;)
I assume you already have virus scanners and other programs that remove these sorts of things?