Update Theme - site down

Followed an update and now get message - "Error thrown
Class ‘CurlyGetValue’ not found. Searched via Google and Bing and no ‘hints’. My site is down and I wish a user could tell me how to roll back the update!

Error thrown

Class ‘CurlyGetValue’ not found

Hi,

Contact with your purchase item author hope they will helped!

Thanks!

The author’s FB page told me to visit here for a solution. Finished a WordPress update to v.5.5 and then the Curly Themes Equestrian site told me there was a new version. CRASH city since. Been to the well for the theme and find myself in a do loop of marketing! Just wondered if a user could help me back to the old version!