hi everyone!
Got Sugar 6.2.0, Apache 2.2.17 and MySQL 5.5.8 working fine for a couple weeks now.

Today - BOOM - I've got that kind of message:
Warning: mysqli_connect() [function.mysqli-connect]: (HY000/2003): Can't connect to MySQL server on 'localhost' (10061) in C:\wamp\...\include\database\MysqliManager.php on line 294
Could not connect to server localhost as root. port . Can't connect to MySQL server on 'localhost' (10061)

All software work fine but I cannot connect to mysql even through Navicat.
I've pulled my hairs off trying to figure out what's happened. Forums, googles - none.
After an hour found some irrelevant thread and got enlightened.

Yesterdeay I have received a letter that we all're going to die if not switching to IPv6.
So I installed IPv6, did some tests and left that protocol in system.

What has helped was deleting it.