Unable to acess the central admin of sharepont 2010/

Hi,

when ever i try to opent the central admin i am getting 503 serivis is not avaliable.

i check the iis and all aplication pool are running state only.but i was not able to acess the CA.can any one suggest me.

to rectify this proble ,i tried to run the configurtion wizard again.

there in 5 th stop i am getting  successfull install the serice:Excel calculation service.it is running form past 5 hours.can you suggust me regarding .it is very very urgent.