In admin/structure/types/
The “Manage Fields, Manage Display, Comment Fields and Comment Display” tabs are missing.

Can anyone help me troubleshoot this issue.
I am running the latest Drupal 7.20

Comments

ensure the core field ui module is enabled in administer -> modules

thanks m8 that was it . I look over the modules a few time but miss that totally

thank you again for pointing out my error....

I had the same problem. Seems to me that this is a bug in 7.20.

why would it be a bug? it's a separate module specifically so the UI can be disabled without disabling the functionality of the fields.module