How did you submit the SAS code to run? From your mention of losing connection to the server it sounds like you are using from front-end tool like SAS/Studio or Enterprise Guide to submit your code.
If you had previously defined Librefs or created WORK datasets and your current SAS session is ended (for whatever reason) then when you establish as new SAS session you will need to redefine those librefs or work datasets before trying to use them.
It could be as simple as resubmitting the code you ran earlier before the disconnect.