Can't Log In to Admin Section - takes me back to website home page

Hallo all! I REALLY hope you guys can help me out!

Okay, so I wanted to install a plug in, so I backed up my database and changed the password because I couldn't remember what it was. Then my store went away and could no longer be accessed. Then I figured out I needed to update my config files with the new password, so I did that and the store came back. But now when I try to login to the administrative section of the site, it kicks me back to my website home page.

I have no clue what I did or how to fix this and I've been searching the web for 2 days trying to find something that's worked. For all I know, I've now done something to create another issue only to be discovered later LOL.

Help?

Thanks!