I opened a file from Dropbox and added several pages of content to it. I went to click save and the program froze. Then my computer seemed to crash and when I started it back up, libreoffice ran recovery, but did not recover the file I had been working on. Is there anything I can do to bring it back? I had three hours worth of work in there 
LibreOffice should offer you to recover your document once you started LibreOffice after crash.
You can check your recovery folder if you go to Tools → Options → LibreOffice → Path. There is location of your backup and temporary files. Just go there to see if anything is there.