page cannot be found HELP PLEASE

Hello, i have a major error with my wordpress site, i dont know what i have done but none of my events or posts are showing up at all. Everytime i try to post a new post the URL is completely wrong and takes me to a page cannot be found.
the site is located at https://www.wigan-pier.co.uk/obb
When i try to post a post and click preview it takes me to https://www.wigan-pier.co.uk/OBB/http:/www.wigan-pier.co.uk/OBB.
It is something to do with the permalinks. I dont know how to restore it to how it originally was. Can anyone please help.
Thank you