Fix an issue with a wordpress webpage

We have an existing webpage which has been unmodified for some time. We recently wish to update our page and have encountered a number of errors within wordpress. We use a theme we believe is outdated and cannot therefore fix the issues we are having which includes the contact form. We wish to keep the theme or have something very similar. Also we want to be able to keep updating the website ourselves once the issues have been fixed.

website is - www.liftdesign.co
current theme is - Rokophoto theme