spry menu bar in dreamweaver keeps displaying in vertical style when its supposed to be horizontal

Code errors probably.  What's the URL to your online page?

Incidentally, Spry was discontinued and removed from DW in 2013.  Nobody uses it anymore.  At this point, you might want to just replace it with a modern navigation system that works well in all devices.  For a Bootstrap example, see correct answer below.

https://community.adobe.com/t5/Dreamweaver/Make-Nav-Bar-Responsive/m-p/10706201#M55701