I want to know if user account enable. I use this code:
var usersList = new List();
DirectoryEntry localMachine = new DirectoryEntr
You're using the WinNT:// provider, which is very limited in its abilities. It doesn't support many of the usual properties that the full-blown LDAP:// provider has - and I would think that's probably the reason why this code setting userAccountControl (which is an LDAP attribute, most likely not present and not support on a local user account) doesn't work.
See Richard Mueller's article WinNT vs. LDAP for a lot more information on what WinNT:// can do (or cannot do)