Hi amit here, The Problem is when i open the lens cover of my SE W700i the camera shows greenish picture everything looks green in colour from the lens of the camera on to the screen of the mobile and after sometime it restarts . please help me....is it a serious problem?

No it was just a software error or change some setting in camera .first you go to camera image settings white balance set it into auto and make sure that any effects is turned on when it is on select off. you can't fix your problem in this method please reset your phone go to setting /general/reset/reset all .Before you reset copy all contacts to the memory card and copy all wanted data to the card then remove memory card from the phone before resetting.it protect your data.another method is simple just remove your battery in the phone when the phone is turned on and keep some minute.after that turn on your phone it will be OK