I have a failed hard drive and the only files that I have left from a knime session are the temporary files. For one specific workflow that I really need I have gigs of data in those temporary files that I suppose are worth something (the workflow name on the temporary directories).
Is there any way to recover any data from those files? Please help! Any attempt is much appreciated!
Sorry, that's all gone. The data in the temp folder is just binary data jumble. The meta data (most importantly the information how to parse that binary data) is/was in main memory until you properly save the workflow.
In the future you can enable the auto-save feature in KNIME (in the preferences) - there is an option to save the data as part of the auto-save copy. Default is not to save it.
In theory it might be possible to set up a new / clean workflow with the same node (and maybe data structure) as your broken one. You would save it in an executed state with dummy values.
You could then try and identify the temporary stored data and switch it out (keep the new name) with one of your file from the temporary folder. This might well involve some back and forth, but could result in getting back some data. This might depend on how much actions you have inserted. In the absence of a Cache node KNIME might split the data over several files and it could be difficult to reconstruct them all if at all possible.
A working backup (think DropBox or something) might be a good idea in the future; but you might have figured that out yourself.