HELP! Theme Options Disappeared!

Hi I’m having a issue with the theme options for my theme. The options would appear in the admin sidebar when I log in, and after a short while after returning I find the theme options button is completely gone! This issue only occurs on my online version of the site (on a hosting server/database). On my local server testing setup (using WAMP server) I have no issues with the theme options button disappearing. How can I solve this?