I doubt you have SHSH blobs saved on your comp using TinyUmbrella. Hence , my only suggestion now for you is to enter DFU mode ( Power button 3 secs , then continue holding power button while pressing down the home button for 10 secs, then let go of the power button while continue pressing the home button) If you follow correctly, you should be able to enter dfu mode.
From there, enter itunes, and hit restore os. If you're using windows hold SHIFT and click restore button on itunes, browse 4.3.5 . Otherwise, you can just click restore directly. (:


This should help you dude.