45 minutes after the last post and I fixed it. Oh well. Don't worry about giving any advice anymore.

Oh my god the relief of not having to search through any more google for the answer.

For anyone wondering, i launched sfm, opened task manager. Expanded SFM. Selected C:\program files (x86)\steam\steamapps\common\source filmmaker\game\sfm.exe then maximised it.

tl;dr:

SFM was permanently minimised. Got maximased again through task manager.