Login in super problem

Hi there

So I stupidly chose a theme that didn’t have a login option at the bottom or anywhere on the page. I’ve tried typing in /wp-admin at the end and that just turns up a page that sayd this:

The page cannot be found
The page you are looking for might have been removed, had its name changed, or is temporarily unavailable.
——————————————————————————–

Please try the following:

?Make sure that the Web site address displayed in the address bar of your browser is spelled and formatted correctly.
?If you reached this page by clicking a link, contact the Web site administrator to alert them that the link is incorrectly formatted.
?Click the Back button to try another link.
HTTP Error 404 – File or directory not found.
Internet Information Services (IIS)

Any ideas as to what I can do to fix it? How do I Login?