Please help. 502 Bad Gateway after altering screen options

Hoping someone can help…

I went to ‘Products’ – ‘Attributes’ – and chose ‘configure terms’ – Then I selected ‘screen options’ and changed the number of attributes that is displayed per page to the maximum of 999.

Now if I try to ‘configure terms’ I get 502 bad gateway. I cant get back into screen options now to lower the number because of the 502 bad gateway when trying to access it ??

Anyone know how I can revert the number??