I switched to a new machine yesterday, and had to reinstall my TeamCity notifier ... so off I went to our TC site to download it, and bam, I was asked for my login ... annoyingly TC maintains it's own password and user accoutns, and then matches these up to NT accounts - so my domain login and password wasn't working, and nor was any previous version of it I could think of.
After much digging around ... I finally found out how to reset a TeamCity password. We have to drop to the command prompt, and use java.exe to fire off a password change.
Firstly, turn off the TeamCity services, or the database will be locked
Next, the basic command we need is: java -cp server.jar;hsqldb.jar ChangePassword <username> <newpassword> <teamcitybuilddir>
Navigate to "<TeamCity home>/webapps/ROOT/WEB-INF/lib"
For this to work we need to point it to an instance of java.exe, and although we can omit the build directory if it is set to default, ours had changed. So our final command is:
C:\TeamCity\jre\bin\java -cp server.jar;hsqldb.jar ChangePassword ccharlto password C:\TeamCityBuild\.BuildServer
Voila a reset password ... 30 minutes of my life wasted, hopefully this will save you that 30 minutes if you have the same problem.