Save button missing on User Account Edit form
Try disabling i18n synchronization module.

There is another question similar to yours. Save button missing from content type edit form
Problem: save button missing from content type edit form. Reason: bug in i18n synchronization module. Solution: none here, but...

There is another case where i18n synchronization causes an infinite loop and there is patch along the lines of

if (function_exists(i18n_sync)) i18n_sync(FALSE);


This is the link, the patch is at #3. https://drupal.org/node/1372500
Maybe that will help you to the right direction.