problem with login/pass

I created the company, entered root login/pass, logged out and i cant enter with this just created login. BEfore this i uninstalled Zoho, becouse i have got the same problem but after using it normally for a few hours. Now i created login with name wich was before unistall and new install and it doesnt work. Ive tryed all the ways. Please help me!
(sorry for my English)