If you have moved your site from one server to the other and have the same domain name, but are experiencing problems with the styles being loaded, here are some tricks that worked for me.
1. Check if there are caching plugins and disable/reenable them.
A caching plugin could be one of the following popular cache plugins:
If possible. Disable these plugins before moving the site.
2. switch themes (reenable your theme)
This actually did the trick for me.
Try switching to another theme, and see if the css is loaded.
Then try to reenable the theme you want to use, and that might give you working styles.
In general: Be very aware og cache! Caching is both a blessing and a curse. So do test on multiple pc's and tools to be sure you are looking at an uncached version. And that is simpler said than done.