If your asking HOW to change the password, you should be able to go into active directory users and computers MMC, click on users, right click administrator and click on reset password. Once you've done, log off, and log back in. this should reset the admin password in your services as well, if it does not, as I know it doesn't for Backup Exec,...
then go to administrative tools, click services, and check all services(or the ones that aren't working properly). under the 'Log On' tab if 'LocalSystem Account' is checked, you should have no worries. If 'This Account' is checked, and the username is administrator, you will need to change the password there to your new password. could be tedious but in less than 10 minutes you should be goodto go!
Hope it helps!