Hi John,
I have never found a problem with any menu not working. However until a moderator is able to offer additional advice, in the meantime you could try:
1. Test your original theme (prior to your changes) by browsing to
https://sitepad.com/themes and then find the name of the theme you installed (eg "Hydro" theme). If the original theme is working, then perhaps you have to undo some changes or reset your theme so that it works again.
2. In your PC browser there will be a 'web developer' addon you can install to help you diagnose and fault find. These are a set of tools which include a tool to view your site in a variety of screen sizes from desktop to mobile.
3. Difficult and probably unnecessary solutions may involve adding 'Custom CSS' to the Primary Menu Style via the 'header' page in your sitepad theme.