login problem

hi
i am stuck so help me developers

this is how i had this problem “my dashboard gives me error this happen after i try to add www to my domain . but then i get this problem but i change my database little and remove that www so my site is running perfectly but i cant access my dashboard”

problem in detail

like
if try to login on http://www.dumlr.com then I come to same page http://www.dumlr.com page without login (it means it redirect me to to that page where I try to login )

and if i try to go to dashboard I get error of

“This web page has a redirect loop

ERR_TOO_MANY_REDIRECTS”

I can see every page except my dashboard