Seems to happen to us somewhat regularly, personalized dashboards...
We do the following, followed by an iisreset. The iisreset has to be done, otherwise the change wont show:
-- See a list of all users that has a personal version of the dashboard.
select T2.tps_name LOGIN_NAME, T2.tps_title USER_TITLE, T3.ui_title DASHBOARD_TITLE
from ui_personalised_dashboard T1, tps_user T2, ui_dashboard T3
where T1.ui_dashboard_guid = T3.ui_guid
and T1.ui_user_guid = T2.tps_guid
order by T2.tps_title
-- Confirm what you are about to delete before you run the third script.
select * from ui_personalised_dashboard
where ui_user_guid in (select tps_guid from tps_user where tps_name = 'LOGIN_NAME')
and ui_dashboard_guid in (select ui_guid from ui_dashboard where ui_title = 'DASHBOARD_TITLE')
-- Delete the personalised version of the Dashboard for specified user.
delete from ui_personalised_dashboard
where ui_user_guid in (select tps_guid from tps_user where tps_name = 'LOGIN_NAME')
and ui_dashboard_guid in (select ui_guid from ui_dashboard where ui_title = 'DASHBOARD_TITLE')