Lost access to making new folder

Granting is just a basic member functionality. Removing etc. would be restricted to contribute or full control access. Are you not the owner of this Team? It def. seems you reduced the permissions of library or someone archived the Team and it got set to read only for members.

It is really hard to say without knowing the issue and you can't really restore the library as it is there, unless it is in the recycle bin, which would be an issue in itself. Unless you have some third party cloud backup solution that allows you to restore the library to a previous state. Not sure how used the library is for that Team but you would probably be just as well to create a new Team, confirm all is working as expected and then utilise the copy or move options within the original library to copy or move into the new library of the new Team. Or sync both libraries using OneDrive and move the files that way.

Thanks

Henry

No I don't have that option. I can't edit user permissions or remove user permissions but i can grant permissions. Do you think I need to restore the library?

I feel like I am missing a trick here too. I will keep thinking and let you know if any other suggestions spring to mind.

Do you have the delete unique permissions option out of interest?

Thanks

Henry