Error Message cant work out why??

please help!!!!!!!!!!!!!!!!!!!!!!! I cant open any word or exel files - comes up preparing to install windows installer then says the update could not be opened verify that the update package exists and you can access it or contact the application vendor to verify this is a valid windows installer package???

 

then it says I dont have enough room to install it, I have removed almost everything I can to make room but it is still saying that, also everything worked on fri but just cant open any word, exel documents. tried to restore but says my computer doesnt have any restore points on it.

 

thanks

 

Helen