If you are not able to get access to a sugarcrm installation you can reset the admin password directly via the sql interface.
First you need to find the active admin account in the database table
users. It has the column
is_admin set to 1 and the column
to active. The code below should return a list of all active admin users.
SELECT user_name FROM users WHERE is_admin = '1' AND status = 'Active';
The password is simply a md5 hash, therefore you can set it to any value you like via:
UPDATE users SET user_hash = MD5('PASSWORD') WHERE user_name = 'USERNAME';