CI Nopb (Need some advice)

Hey guys

I have just taken over a site for a client which is built on CI by a previous company which I have never dealt with before - Once I uploaded to my server and got the site running the admin side did not allow me to log in anymore. It can tell I am a user with the correct credentials but it just redirects back on itself to the login page again.

Any help or advice would be appreciated and I am sorry for the vagueness with the information but I am a total novice with this.

Cheers

Josh