Admin panel not working (login problem)

Halo everyone..

I am facing a problem since from two days i.e., i have installed two wordpress (English and Arabic) on a same domain.. Now admin panel of English wordpress is working perfectly but i am not able to logged in admin panel of Arabic wordpress.. in arabic wordpress it demands user and password.. but when i enter user and password and press login the blank page appears…
anyone can help plzz..

regards,
Junaid Munir