I have managed to mess up my user roles and need to restore them to the original.

I believe this might be done in the wp_usermeta but I have no idea what to do.

Any help here would be awesome as I am really pulling my hair out with it.

how new is your site? If it is very new, you might be best just reinstalling Wordpress.
What vrsion of WP?

Hiya mate. My site isn't a new install and a fresh install would really be out of the question. I'm using the latest version of WP

Any ideas?

how many users do you have? Could you delete them all except for admin and clean out all the rows in wp_usermeta table except thoes associated with the ADMIN user?

For each user there is one row in the wp_user table and each user has an ID with admin being number 1. In the wp_usermeta table there can be many rows for each user in the wp_user table. Each row has it's unique UMETA_ID and a field called USER_ID that matches the ID field in the wp_user table.

You can have one user with 5 rows in the wp_usermeta table, while another has 17 rows associated with it. It all depends on what has happened with that user.