Permalink & Admin Login Issues

I need help if possible!

Ok i need to upgrade my wordpress BUT before i can do that i need to fix this issue.

Basically i updated the permalink structure about 2 weeks ago using /%postname%/%year%/%monthnum%/%day%/. After reading tonight it looks like it was the wrong way to do it ie: should have had month/day/year etc.. first.

Anyway it has all been working great, the site still works including posts, pages, links etc.. BUT i cannot login to admin. IT WAS working and has been until tonight! I haven’t changed anything for weeks since the permalink change and could log in without issues. I have done a search and spent hours trying to find a fix and nothing is working.

When i try to login as admin ie: wp-login.php? it goes to a “page cannot be found” error. If i go to wp-login.php?loggedout=true it shows that page BUT as soon as i try to login i get the error page.

Can anyone help me PLEASE? I cannot update my website and have no idea what/where/how to fix this.

Thanks