I have a thread on this somewhere else. If you're like me your Skyrim install resorts to opening what looks like a small command window which closes immediately, then the screen appears to be switching modes, followed immediately by the desktop again, and you never see the Bethesda logo come up, no music, etc.
I tried everything. Nothing worked until I deleted d3d9.dll, and a couple of other files obviously associated with ENB by their names - enbxxx.ini and another one, all in the root directory of Skyrim, which was C:\program files\steam\steamapps\common\skyrim. I also deactivated and uninstalled the ENB mod from Nexus Mod Manager.
Following this, I had to go to the ENB website and download the latest version of ENB's base installation. Version 1.9 or something, and install that. Once that was done, the game started up no problem. If you want to use an ENB mod at that point, you have to use one built on either that base version or later, because earlier ones aren't compatible with the latest version of Skyrim after early November's update. One that I am using now is the Seasons of Skyrim ENB mod that can be found at the Skyrim Nexus website.
Hope this helps.