At the moment I am running version 1.3.10 of skyrim, on PC, with steam. However, it seems that steam is not downloading patch 1.4, even though auto-update is enabled. I am currently experiencing a bug that should be fixed in 1.4 (the ending of "A night to remember"), but since I am still running 1.3, I cannot finish that quest.

Is it possible to do a update manually, or to force steam to patch skyrim?

Have you tried verifying game cache?

Yes, verifying game cache should fix you up.
Don't forget, this is like re-installing the game...
It will also re-detect your video, write new (default) .ini files, and reset your game settings (ie. level of difficulty).

At some point I verified my own game cache files. I had been playing on Master difficulty - my difficulty was then reset to Adept!
I didn't catch on for days...
It was a pathetic slaughter.