Hi guys, I'm having alot of trouble trying to restore my iphone. I jailbroke it with redsn0w. i want to get rid of it, since it's untethered jailbreak. so when i try to restore it, it gives me this error:

The iphone ".." could not be restored. This device isn't eligible for the requested build.

I tried going to 4.3.4, wouldn't work, then tried 4.3.5 and it wouldn't work. but if i go to like 5.0 it will become a brick right? anyways i tried using tinyumbrella and unchecking the "set hosts to cydia on exit" and it still doesn't work. I've looked all over and nothing seems to work. My itunes is the newest version too.. Can someone help?