Open Cart 1.5.6 check out fix error

Need opencart tech who would fix our check-out page. It never give us any issues in the past. We have a well designed professional template and we never had any check out issues before. Recently we had to restore from back-up and the site worked well, 2 days later out of nowhere we get this check out error - /[login to view URL] (The page you requested cannot be found!). We have SSL certificates (2 certificates installed one for images and one for site domain) well installed and they never been changed/still valid. I checked config and admin/config files and they appear to be ok as well. Currently customer cannot check out because of that page. Simple project for OpenCart expert. Something is clearly missing there since it is not directing to correct payment credit card page.