Preview and Mail messages are blank after El Capitan upgrade.  Favorite folders that I’ve dragged to Finder side bar are not there when I want to save or upload a file.

I’m using a MB Air 2015.

Since upgrading, when I try to open a Mail message or Preview, both applications fail to open and the preview of the items to open are blank.

Are there any known fixes?

Also, I have the folders I commonly used dragged to the Finder sidebar.  In the Finder window those folders are there but when I want to Save or Upload anything and a box opens, those folders are not there (usually just Remote Disk).

How can I resolve this so my most-used folders are there when I want to open, save, or upload a file?